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5. Light soaking effects on full-area and half-cut silicon heterojunction solar cells

Author

Pingel, Sebastian, Steinmetz, Anamaria, Bivour, Martin, Roder, Sebastian, Vulcanean, Ioan Voicu, Zimmermann, Karin, Wolke, Winfried, Georgiou-Sarlikiotis, Vasileios, Tutsch, Leonard, Wenzel, Timo, Erath, Denis, Lorenz, Andreas, Münzer, Anna, Baliozian, Puzant, Richter, Armin, Rößler, Torsten, Fokuhl, Esther, Gebhardt, Paul, Rentsch, Jochen, Schneider, Jale, Clement, Florian, Nekarda, Jan, and Preu, Ralf

Published
2023
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6. Study of GHz-Burst Femtosecond Laser Micro-Punching of 4H-SiC Wafers

Author

Mir, Hanan, Meyer, Fabian, Brand, Andreas A., Erath-Dulitz, Katrin, and Nekarda, Jan Frederik

Abstract

The micromaching of silicon carbide using femtosecond laser pulses is becoming an important field of research. High-repetition-rate sub-pulse trains, so-called pulse bursts, are a particularly promising route towards completely new process regimes. We report on the results of micro-punching n-type 4H-silicon carbide wafers using GHz pulse burst in order to systematically investigate the influence of the temporal energy distribution on laser processing. Pulse-burst experiments are performed at a laser wavelength of λ= 1030 nm using a single GHz burst containing a varying number of pulses and then compared with standard single femtosecond pulse exposures. The pulse energy is swept across the ablation threshold. For each set of parameters, the micromachining efficiency is evaluated in terms of ablation efficiency and burr characteristics. Scanning electron micrographs provide qualitative information about the machining quality. The characteristics of the laser modification are discussed in relation to an increase in the number of pulses in a burst envelope and to an increase in pulse energy. We observe that, compared to a single pulse, a GHz burst comprised of 10 lower-energy pulses leads to an increase in the ablation rate by a factor of ≤ 10.

Published
2023
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21. Measuring U.S. labor market dynamics

Author

Nekarda, Christopher J.

Subjects
UCSD. Economics. (Discipline) Dissertations, Academic, United States. Econometric models Labor market, United States. Econometric models Measurement Labor mobility, Time-series analysis
Abstract

This dissertation develops new data and methods for properly measuring U.S. labor market dynamics using large, nationally-representative household surveys. These data are used to assess potential biases arising from time aggregation and from geographic mobility. Time aggregation is estimated using weekly labor force information from the Survey of Income and Program Participation (SIPP). The degree of time aggregation is large: gross flows estimated from monthly data understate the true number of transitions by 20 percent on average. However, time aggregation creates no meaningful cyclical bias in measured gross flows or hazard rates. Separation hazard rates calculated from the SIPP and the Current Population Survey (CPS) are strongly countercyclical and remain so after adjusting for time aggregation. Using a new database that captures all longitudinal information in the CPS individuals who move can be identified. Comparing the behavior of the entire CPS sample with the subset known not to have moved provides a bound to the bias from geographic mobility. The cyclical bias from geographic mobility is small. At business cycle frequencies, the difference between the separation hazard rate calculated from the entire CPS sample and from a subset that are known not to have moved never exceeds 4 percent. There is little effect of mobility on the job finding hazard rate. The weekly SIPP data identify direct employment-to- employment (EE) transitions. Abstracting from labor force participation, EE transitions account for one-half of all separations from employment. Similar estimates using the CPS are twice as large however the CPS overstates EE transitions because of time aggregation. Separations to a new job are strongly procyclical while separations to unemployment are strongly countercyclical. The combination yields a nearly acyclical total separation rate. The weekly job finding rate is strongly procyclical

Published
2008

25. Abstract

Author

Mache, Ch., Urban, Ch., Sauer, H., Brandesky, G., Meßner, H., Grienberger, H., Becker, H., Slave, I., Hauer, Ch., Pakisch, B., Oberbauer, R., Mokry, M., Ebner, F., Kleinert, R., Schiller, D., Kasparu, H., Schneider, G., Sega, W., Lutz, D., Mader, R. M., Steger, G. G., Sieder, A. E., Ovissi, L., Roth, E., Hamilton, G., Jakesz, R., Rainer, H., Schenk, T., Kornek, G., Schulz, F., Depisch, D., Rosen, H., Sebesta, Ch., Scheithauer, W., Locker, G. J., Czernin, J., Derfler, K., Gnant, M., Schiessel, R., Petru, E., Pickel, H., Heydarfadai, M., Lahousen, M., Haas, J., Sagaster, P., Flamm, J., Umek, H., Essl, R., Teich, G., Micksche, M., Ludwig, H., Ambros, P. F., Lestou, V., Strehl, S., Mann, G., Gadner, H., Eibl, B., Greiter, E., Grünewald, K., Gastl, G., Thaler, J., Aulitzky, W., Lion, T., Henn, T., Gaiger, A., Hofmann, J., Wolf, A., Spitaler, M., Ludescher, Christof, Grunicke, H., Mitterbauer, G., Stangl, E., Geissler, K., Jäger, U., Lechner, K., Mannhalter, C., Haas, Oskar A., Tirita, Anthi, Kahls, P., Haas, O., Hinterberger, W., Linkesch, W., Pober, Michael, Fae, Ingrid, Kyrle, Alexander, Neumeister, Andrea, Panzer, Simon, Kandioler, D., End, A., Grill, R., Karlic, H., Inhauser, T., Chott, A., Pirc-Danoewinata, H., Klepetko, W., Heinz, R., Hopfinger-Limberger, G., Koller, E., Schneider, B., Pittermann, E., Lorber, C., Eichinger, S., Neumann, E., Weidinger, J., Gisslinger, H., Bedford P., Jones D., Cawley J., Catovsky D., Bevan P., Scherrer, R., Bettelheim, P., Knöbl, P., Kyrie, P. A., Lazcika, K., Schwarzinger, I., Sillaber, C., Watzke, H., Dávid, M., Losonczy, H., Matolcsy, A., Papp, M., Prischl, F. C., Schwarzmeier, J. D., Zoubek, Andreas, Harbott, Jochen, Ritterbach, Jutta, Ritter, Jörg, Sillaber, Ch., Agis, H., Spanblöchl, E., Sperr, W. R., Valent, P., Czerwenka, K., Virgolini, I., Li, S. R., Müller, M., Wrann, M., Gaggl, S., Fasching, B., Herold, M., Geissler, D., Nachbaur, D., Huber, Ch., Schwaighofer, H., Pichl, M., Niederwieser, D., Gilly, B., Weissel, H., Lorber, Ch., Schwarzmeier, J., Gasché, C., Reinisch, W., Hilgarth, M., Keil, F., Thomssen, C., Kolb, H. J., Holler, E., Wilmanns, W., Tilg, H., Gächter, A., Panzer-Grümayer, E. R., Majdic, O., Kersey, J. H., Petzer, A. L., Bilgeri, R., Zilian, U., Geisen, F. H., Haun, M., Konwalinka, G., Fuchs, D., Zangerle, R., Artner-Dworzak, E., Weiss, G., Fritsch, P., Tilz, G. P., Dierich, M. P., Wachter, H., Schüller, J., Czejka, M. J., Jäger, W., Meyer, B., Weiss, C., Schernthaner, G., Marosi, Ch., Onderka, E., Schlögl, B., Maca, T., Hanak, R., Mannhalter, Ch., Brenner, B., Mayer, R., Langmann, A., Langmann, G., Slave, J., Poier, E., Stücklschweiger, G., Hackl, A., Fritz, A., Pabinger, I., Willfort, A., Groiss, E., Bernhart, M., Waldner, R., Krieger, O., Nowotny, H., Strobl, H., Michlmayr, G., Mistrik, M., lstvan, L., Kapiotis, S., Laczika, K., Speiser, W., Granena, A., Hermans, J., Zwaan, F., Gratwohl, A., Labar B., Mrsić M., Nemet D., Bogdanić V., Radman I., Zupančić-Šalek Silva, Kovačević-Metelko Jasna, Aurer I., Forstinger, C., Scholten, C., Kier, P., Kalhs, P., Schwinger, W., Slavc, I., Lackner, H., Nussbaumer, W., Fritsch, E., Fink, M., Zechner, O., Kührer, I., Kletter, V., Frey, S., Leitgeb, C., Fritz, E., Silly, H., Brezinschek, R., Kuss, I., Stöger, H., Schmid, M., Samonigg, H., Wilders-Truschnig, M., Schmidt, F., Bauernhofer, T., Kasparek, A. K., Ploner, F., Stoeger, H., Moser, R., Leikauf, W., Klemm, F., Pfeffel, F., Niessner, H., Poschauko, H., Pojer, E., Locker, G. J., Braun, J., Gnant, M. F. X., Michl, I., Pirker, R., Liebhard, A., Zielinski, C., Dittrich, C., Bernát, S. I., Pongrácz, E., Kastner, J., Raderer, M., Jorbenyi, Z., Yilmaz, A., Suardet, L., Lahm, H., Odartchenko, N., Varga, Gy., Sréter, L. A., Oberberg, D., Berdel, W. E., Budiman, R., Brand, C., Berkessy, S., Radványi, G., Pauker, Zs., Nagy, Zs., Karádi, Å., Serti, S., Hainz, R., Kirchweger, P., Prager, C., Prada, J., Neifer, S., Bienzle, U., Kremsner, P., Kämmerer, B., Vetterlein, M., Pohl, W., Letnansky, K., Imre, S. G., Parkas, T., Lakos, Zs., Kiss, A., Telek, B., Felszeghy, E., Kelemen, E., Rak, K., Pfeilstöcker, M., Reisner, R., Salamon, J., Georgopoulos, A., Feistauer, S., Georgopoulos, M., Graninger, W., Klinda, F., Hrubisko, M., Sakalova, A., Weißmann, A., Röhle, R., Fortelny, R., Gutierrez, F., Fritsch, G., Printz, D., Buchinger, P., Buchinger, P., Hoecker, P., Peters, C., Gebauer, E., Katanić, D., Nagy, Á., Szomor, Á., Med. J., Batinić D., Užaervić B., Marušić M., Kovačoević-Metelko Jasminka, Jakić-Razumović Jasminka, Kovačević-Metelko Jasminka, Zuoancić-Šalek Silva, Ihra, G. C., Reinisch, W. W., Hilgarth, M. F., Schwarzmeier, I. D., Várady, E., Molnár, Z. S., Fleischmann, T., Borbényi, Z., Bérczi, M., István, L., Szerafin, L., Jakó, J., Bányai, A., Dankó, K., Szegedi, Gy., Neubauer, M., Frudinger, A., Scholten, Ch., Forstinger, Ch., Dobrić I., Willheim, M., Szépfalusi, Z., Mader, R., Boltz, G., Schwarzmeier, J. D., Nahajevszky, S., Téri, N., Póth, I., Nagy, P., Smanykó, D., Babicz, T., Ujj, Gy., Iványi, J. L., Tóth, F. D., Kiss, J., Konja, J., Petković, I., Kardum, I., Kaštelan, M., Kelečić, J., Feminić, R., Djermanović, M., Bilić, E., Jakovljević, G., Peter, B., Gredelj, G., Senji, P., Thalhammer, F., Floth, A., Etele-Hainz, A., Kainberger, F., Radaszkiewicz, T., Kierner, H., Mód, Anna, Pitlik, E., Gottesman, M., Magócsi, Mária, Sarkadi, B., Knapp, S., Purtscher, B., DelleKarth, G., Jaeger, U., Krieger, O., Berger, W., Elbling, L., Ludescher, C., Hilbe, W., Eisterer, W., Preuß, E., Izraeli, S., Janssen, J. W. G., Walther, J. U., Kovar, H., Ludwig, W. D., Rechavi, G., Bartram, C. R., Rehberger, A., Mittermayer, F., Schauer, E., Kokoschka, E. M., Kammerer, B., Kokron, E., Desser, L., Abdul-Hamid, G., Kroschinksky, F., Luther, Th., Fischer, H., Nowak, R., Wolf, H., Fleischer, J., Wichmann, G., Albercht, S., Adorf, D., Kaboth, W., Nerl, C., Aman, J., Rudolf, G., Peschel, C., Anders, O., Burstein, Ch., Ernst, B., Steiner, H., Konrad, H., Annaloro, U. P., Mozzana, C., Butti, R., Della, C., Volpe A., Soligo D., Uderzo M., Lambertenghi-Deliliers G., Ansari, H., Dickson, D., Hasford, J., Hehlmann, R., Anyanwu, E., Krysa, S., Bülzebrück, H., Vogt-Moykopf, I., Arning, M., Südhoff, Th., Kliche, K. O., Wehmeier, A., Schneider, W., Arnold, R., Bunjes, D., Hertenstein, B., Hueske, D., Stefanic, M., Theobald, M., Wiesneth, M., Heimpel, H., Waldmann, H., Arseniev, L., Bokemeyer, C., Andres, J., Könneke, A., Papageorgiou, E., Kleine, H. -D., Battmer, K., Südmeyer, I., Zaki, M., Schmoll, H. -J., Stangel, W., Poliwoda, H., Link, H., Aul, C., Runde, V., Heyll, A., Germing, U., Gattermann, N., Ebert, A., Feinendegen, L. E., Huhn, D., Bergmann, L., Dönner, H., Hartlapp, J. H., Kreiter, H., Schuhmacher, K., Schalk T., Sparwasser C., Peschel U., Fraaß C. Huber, HIadik, F., Kolbe, K., Irschick, E., Bajko, G., Wozny, T., Hansz, J., Bares, R., Buell, U., Baumann, I., Harms, H., Kuse, R., Wilms, K., Müller-Hermelink, H. K., Baurmann, H., Cherif, D., Berger, R., Becker, K., Zeller, W., Helmchen, U., Hossfeld, D. K., Bentrup, I., Plusczyk, T., Kemkes-Matthes, B., Matthes, K., Bentz, M., Speicher, M., Schröder, M., Moos, M., Döhner, H., Lichter, P., Stilgenbauer, S., Korfel, A., Harnoss, B. -M., Boese-Landgraf, J., May, E., Kreuser, E. -D., Thiel, E., Karacas, T., Jahn, B., Lautenschläger, G., Szepes, S., Fenchel, K., Mitrou, P. S., Hoelzer, D., Heil, G., Lengfelder, E., Puzicha, E., Martin, H., Beyer, J., Kleiner, S., Strohscheer, I., Schwerdtfeger, R., Schwella, N., Schmidt-Wolf, I., Siegert, W., Weyer, C., arzen, G., Risse, G., Miksits, K., Farshidfar, G., Birken, R., Schilling, C. v., Brugger, W., Holldack, J., Mertelsmann, R., Kanz, L., Blanz, J., Mewes, K., Ehninger, G., Zeller, K. -P., Böhme. A., Just G., Bergmann. L., Shah P., Hoelzer D., Stille W., Bohlen, H., Hopff, T., Kapp, U., Wolf, J., Engert, A., Diehl, V., Tesch, H., Schrader, A., van Rhee, J., Köhne-Wömpner, H., Bokemeyer', C., Gonnermann, D., Harstrick, A., Schöffski, P., van Rhee, J., Schuppert, F., Freund, M., Boos, J., Göring, M., Blaschke, G., Borstel, A., Franke, A., Hüller, G., Uhle, R., Weise, W., Brach, Marion A., Gruss, Hans-Jürgen, Herrmann, Friedhelm, deVos, Sven, Brennscheidt, Ulrich, Riedel, Detlev, Klch, Walter, Bonlfer, Renate, Mertelsmann, Roland, Brieaer, J., Appelhans, H., Brückner, S., Siemens, HJ., Wagner, T., Moecklin, W., Mertelsmann, R., Bertz, H., Hecht, T., Mertelsmann, R., Bühl, K., Eichelbaum, M. G., Ladda, E., Schumacher, K., Weimer, A., Bühling, F., Kunz, D., Lendeckel, U., Reinhold, D., Ulmer, A. J., Flad, H. -D., Ansorge, S., Bühring, Hans-Jörg, Broudy¶, Virginia C., Ashman§, Leonie K., Burk, M., Kunecke, H., Dumont, C., Meckenstock, G., Volmer, M., Bucher, M., Manegold, C., Krenpien, B., Fischer, J. R., Drings, P., Bückner, U., Donhuijsen-Ant, R., Eberhardt, B., Westerhausen, M., Busch, F. W., Jaschonek, K., Steinke, B., Calavrezos, A., Hausmann, K., Solbach, M., Woitowitz, H. -P., Hilierdal, G., Heilmann, H. -P., Chen, Z. J., Frickhofen, N., Ellbrück, D., Schwarz, T. F., Körner, K., Wiest, C., Kubanek, B., Seifried, E., Claudé, R., Brücher, J., Clemens, M. R., Bublitz, K., Bieger, O., Schmid, B., Clemetson, K. J., Clemm, Ch., Bamberg, M., Gerl, A., Weißbach, L., Danhauser-Riedl, S., Schick, H. D., Bender, R., Reuter, M., Dietzfelbinger, H., Rastetter, J., Hanauske, A. -R., Decker, Hans-Jochen, Klauck, Sabine, Seizinger, Bernd, Denfeld, Ralf, Pohl, Christoph, Renner, Christoph, Hombach, Andreas, Jung, Wolfram, Schwonzen, Martin, Pfreundschuh, Michael, Derigs, H. Günter, Boswell, H. Scott, Kühn, D., Zafferani, M., Ehrhardt, R., Fischer, K., Schmitt, M., Witt, B., Ho, A. D., Haas, R., Hunstein, W., Dölken, G., Finke, J., Lange, W., Held, M., Schalipp, E., Fauser, A. A., Mertelsmann, R., Donhuijsen, K., Nabavi, D., Leder, L. D., Haedicke, Ch., Freund, H., Hattenberger, S., Dreger, Peter, Grelle, Karen, Schmitz, Norbert, Suttorp, Meinolf, Müller-Ruchholtz, Wolfgang, Löffler, Helmut, Dumoulin, F. L., Jakschies, D., Walther, M., Hunger, P., Deicher, H., von Wussow, P., Dutcher, J. P., Ebell, W., Bender-Götze, C., Bettoni, C., Niethammer, D., Reiter, A., Sauter, S., Schrappe, M., Riehm, H., Niederle, N., Heidersdorf, H., Müller, M. R., Mengelkoch, B., Vanhoefer, U., Stahl, M., Budach, V., loehren, B., Alberti, W., Nowrousian, M. R., Seeber, S., Wilke, H., Stamatis, G., Greschuchna, D., Sack, H., Konietzko, N., Krause, B., Dopfer, R., Schmidt, H., Einsele, H., Müller, C. A., Goldmann, S. F., Grosse-Wilde, H., Waller, H. D., Libal, B., Hohaus, S., Gericke, G., von Eiff, M., Oehme, A., Roth, B., van de Loo, J., von Eiff, K., Pötter, R., Weiß, H., Suhr, B., Koch, P., Roos, H., van de Loo, J., Meuter, V., Heissig, B., Schick, F., Duda, S., Saal, J. G., Klein, R., Steidle, M., Eisner, S., Ganser, A., Seipelt, G., Leonhardt, M., Engelhard, M., Brittinger, G., Gerhartz, H., Meusers, P., Aydemir, Ü., Tintrup, W., Tiemann, H., Lennert, K., Esser, B., Hirsch, F. W., Evers, C., Riess, H., Lübbe, A., Greil, R., Köchling, A., Digel, D., Bross, K. J., Dölken, G., Mertelsmann, R., Gencic S., Ostermann, M., Baum, R. P., Fiebig, H. H., Berger, D. P., Dengler, W. A., Winterhalter, B. R., Hendriks, H., Schwartsmann, G., Pinedo, H. M., Ternes, P., Mertelsmann, R., Dölken, G., Fischbach, W., Zidianakis, Z., Lüke, G., Kirchner, Th., Mössner, J., Fischer, Thomas, Haque, Saikh J., Kumar, Aseem, Rutherford, Michael N., Williams, Bryan R. G., Flohr, T., Decker, T., Thews, A., Hild, F., Dohmen, M., von Wussow, P., Grote-Metke, A., Otremba, B., Fonatsch, C., Binder, T., Imhof, C., Feller, A. C., Fruehauf, S., Moehle, R., Hiddemann Th., Büchner M. Unterhalt, Wörmann, B., Ottmann, O. G., Verbeek, G. W., Seipelt A. Maurer, Geissler, G., Schardt, C., Reutzel, R., Hiddemann, W., Maurer, A., Hess, U., Lindemann, A., Frisch, J., Schulz, G., Mertelsmann, R., Hoelzer, P., Gassmann, W., Sperling, C., Uharek, L., Becher, R., Weh, H. J., Tirier, C., Hagemann, F. G., Fuhr, H. G., Wandt, H., Sauerland, M. C., Gause, A., Spickermann, D., Klein, S., Pfreund-schuh, M., Gebauer, W., Fallgren-Gebauer, E., Geissler, R. G., Mentzel, U., Kleiner, K., Rossol, R., Guba, P., Kojouharoff, G., Gerdau, St., Körholz, D., Klein-Vehne, A., Burdach, St., Gerdemann M., Maurer J., Gerhartz, H. H., Schmetzer, H., Mayer, P., Clemm, C., Hentrich, M., Hartenstein, R., Kohl, P., Gieseler, F., Boege, F., Enttmann, R., Meyer, P., Glass, B., Zeis, M., Loeffler, H., Mueller-Ruchholtz, W., Görg, C., Schwerk, W. B., Köppler, H., Havemann, K., Goldschmitt, J., Goldschmidt, H., Nicolai, M., Richter, Th., Blau, W., Hahn, U., Kappe, R., Leithäuser, F., Gottstein, Claudia, Schön, Gisela, Dünnebacke, Markus, Berthold, Frank, Gramatzki, M., Eger, G., Geiger, M., Burger, R., Zölch, A., Bair, H. J., Becker, W., Griesinger, F., Elfers, H., Griesser, H., Grundner-Culemann, E., Neubauer, V., Fricke, D., Shalitin, C., Benter, T., Mertelsmann, R., Dölken, Gottfried, Mertelsmann, Roland, Günther, W., Schunmm, M., Rieber, P., Thierfelder, S., Gunsilius, E., Kirstein, O., Bommer, M., Serve, H., Hülser, P. -J., Del Valle F., Fischer J. Th., Huberts H., Kaplan E., Haase, D., Halbmayer, W. -M., Feichtinger, Ch., Rubi, K., Fischer, M., Hallek, M., Lepislo, E. M., Griffin, J. D., Emst, T. J., Druker, B., Eder, M., Okuda, K., D.Griffin, J., Kozłowska-Skrzypczak, K., Meyer, B., Reile, D., Scharnofske, M., Hapke, G., Aulenbacher, P., Havemann, K., Becker, N., Scheller, S., Zugmaier, G., Pralle, H., Wahrendorf, J., Heide, Immo, Thiede, Christian, de Kant, Eric, Neubauer, Andreas, Herrmann, Richard, Rochlitz, Christoph, Heiden, B., Depenbrock, H., Block, T., Vogelsang, H., Schneider, P., Fellbaum, Ch., Heidtmann, H. -H., Blings, B., Havemann, K., Fackler-Schwalbe, E., Schlimok, G., Lösch, A., Queißer, W., Löffler, B., Kurrle, E., Chadid, L., Lindemann, A., Mertelsmann, R., Nicolay, U., Gaus, W., Heinemann, V., Jehn, U., Gleixner, B., Wachholz, W., Scholz, P., Plunkett, W., Heinze, B., Novotny, J., Hess, Georg, Gamm, Heinold, Seliger, Barbara, Heuft, H. G., Oettle, H., Zeiler, T., Eckstein, R., Heymanns, J., Havemann, K., Hladik, F., Hoang-Vu, C., Horn, R., Cetin, Y., Scheumann, G., Dralle, H., Köhrle, J., von zur Mühlen, A., Brabant, G., Hochhaus, A., Mende, S., Simon, M., Fonatsch, Ch., Heinze, B., Georgii, A., Hötzl, Ch., Hintermeier-Knabe, R., Kempeni, J., Kaul, M., Hoetzl, Ch., Clemm, Ch., Lauter, H., Hoffknecht, M. M., Eckardt, N., Hoffmann-Fezer, G., Gall, C., Kranz, B., Zengerle, U., Pfoersich, M., Birkenstock, U., Pittenann, E., Heinz, B., Hosten, N., Schörner, W., Kirsch, A., Neumann, K., Felix, R., Humpe, A., Kiss, T., Trümper, L. H., Messner, H. A., Hundt, M., Zielinska-Skowronek, M., Schubert, J., Schmidt, R. E., Huss, R., Storb, R., Deeg, H. J., Issels, R. D., Bosse, D., Abdel-Rahman, S., Jaeger, M., Söhngen, D., Weidmann, E., Schwulera, U., Jakab, I., Fodor, F., Pecze, K., Jaques, G., Schöneberger, H. -J., Wegmann, B., Grüber, A., Bust, K., Pflüger, K. -H., Havemann, K., Faul, C., Wannke, B., Scheurlen, M., Kirchner, M., Dahl, G., Schmits, R., Fohl, C., Kaiser, U., Tuohimaa, P., Wollmer, E., Aumüller, G., Havemann, K., Kolbabek, H., Schölten, C., Popov-Kraupp, B., Emminger, W., Hummel, M., Pawlita, M., v.Kalle, C., Dallenbach, F., Stein, H., Krueger, G. R. F., Müller-Lantzsch, N., Kath, R., Höffken, K., Horn, G., Brockmann, P., Keilholz, U., Stoelben, E., Scheibenbogen, C., Manasterski, M., Tilgen, W., Schlag, P., Görich, J., Kauffmann, G. W., Kempter, B., Rüth, S., Lohse, P., Khalil, R. M., Hültner, L., Mailhammer, R., Luz, A., Hasslinger, M. -A., Omran, S., Dörmer, P., Kienast, J., Kister, K. P., Seifarth, W., Klaassen, U., Werk, S., Reiter, W. W., Klein, G., Beck-Gessert, S., Timpl, R., Hinrichs, H., Lux, E., Döring, G., Scheinichen, D., Döring, G., Wernet, P., Vogeley, K. T., Richartz, G., Südhoff, T., Horstkotte, D., Klocker, J., Trotsenburg, M. v., Schumer, J., Kanatschnig, M., Henning, K., Knauf, W. U., Pottgießer, E., Raghavachar, A., Zeigmeister, B., Bollow, M., Schilling, A., König, H., Koch, M., Volkenandt, M., Seger, Andrea, Banerjee, D., Vogel, J., Bierhoff, E., Heidi, G., Neyses, L., Bertino, J., Kocki, J., Rozynkowa, D. M., M.Rupniewska, Z., Wojcierowski, J., König, V., Hopf, U., Koenigsmann, M., Streit, M., Koeppen, K. M., Martini, I., Poppy, U., Hardel, M., Havemann, K., Havemann, K., Clemm, Ch., Wendt, Th., Gauss, J., Kreienberg, R., Hohenfellner, R., Krieger, O., Istvan, L., Komarnicki, M., Kazmierczak, M., Haertle, D., Korossy, P., Haus, S. Kotlarek, Gabryś, K., Kuliszkiewicz-Janus, M., Krauter, J., Westphal, C., Werner, K., Lang, P., Preissner, K. T., Völler, H., Schröder, K., Uhrig, A., Behles, Ch., Seibt-Jung, H., Besserer, A., Kreutzmann, H., Kröning, H., Kähne, T., Eßbach, U., Kühne, W., Krüger, W. H., Krause, K., Nowicki, B., Stockschläder, M., Peters, S. O., Zander, A. R., Kurowski, V., Schüler, C., Höher, D., Montenarh, M., Lang, W., Schweiger, H., Dölken, Gottfried, Lege, H., Dölken, G., Wex, Th., Frank, K., Hastka, J., Bohrer, M., Leo, R., Peest, D., Tschechne, B., Atzpodien, J., Kirchner, H., Hein, R., Hoffmann, L., Stauch, M., Franks, C. R., Palmer, P. A., Licht, T., Mertelsmann, R., Liersch, T., Vehmeyer, K., Kaboth, U., Maschmeyer, G., Meyer, P., Helmerking, M., Schmitt, J., Adam, D., Prahst, A., Hübner, G., Meisner, M., Seifert, M., Richard, D., Yver, A., Spiekermann, K., Brinkmann, L., Battmer, K., Krainer, M., Löffel, J., Stahl, H., Wust, P., Lübbert, M., Schottelius, A., Mertelsmann, R., Henschler, R., Mertelsmann, R., Mapara, M. Y., Bargou, R., Zugck, C., Krammer, P. H., Dörken, B., Maschek, Hansjörg, Kaloutsi, Vassiliki, Maschek, Hansjörg, Gormitz, Ralf, Meyer, P., Kuntz, B. M. E., Mehl, B., Günther, I., Bülzebruck, H., Menssen, H. D., Mergenthaler, H. -G., Dörmer, P., Heusers, P., Zeller, K. -P., Enzinger, H. M., Neugebauer, T., Klippstein, T., Burkhardt, K. L., Putzicha, E., Möller, Peter, Henne, Christof, Eichelmann, Anette, Brüderlein, Silke, Dhein, Jens, Möstl, M., Krieger, O., Mucke, H., Schinkinger, M., Moiling, J., Daoud, A., Willgeroth, Ch., Mross K., Bewermeier P., Krüger W., Peters S., Berger C., Bohn, C., Edler, L., Jonat, W., Queisser, W., Heidemann, E., Goebel, M., Hamm, K., Markovic-Lipkovski, J., Bitzer, G., Müller, H., Oethinger, M., Grießhammer, M., Tuner, I., Musch E., Malek, M., Peter-Katalinic, J., Hügl, E., Helli, A., Slanicka, M., Filipowicz, A., Nissen, C., Speck, B., Nehls, M. C., Grass, H. -J., Dierbach, H., Mertelsmann, R., Thaller, J., Fiebeler, A., Schmidt, C. A., O'Bryan, J. P., Liu, E., Ritter, M., de Kant, E., Brendel, C., He, M., Dodge, R., George, S., Davey, F., Silver, R., Schiffer, C., Mayer, R., Ball, E., Bloomfield, C., Ramschak, H., Tiran, A., Truschnig-Wilders, M., Nizze, H., Bühring, U., Oelschlägel, U., Jermolow, M., Oertel, J., Weisbach, V., Zingsem, J., Wiens, M., Jessen, J., Osthoff, K., Timm, H., Wilborn, F., Bodak, K., Langmach, K., Bechstein, W., Blumhardt, G., Neuhaus, P., Olek, K., Ottinger, H., Kozole, G., Belka, C., Meusers, P., Hense, J., Papadileris, Stefan, Pasternak, G., Pasternak, L., Karsten, U., Pecherstorfer, M., Zimmer-Roth, I., Poloskey, A., Petrasch, S., Kühnemund, O., Uppenkamp, M., Lütticken, R., Kosco, M., Schmitz, J., Petrides, Petro E., Dittmann, Klaus H., Krieger, O., Pflueger, K. -H., Grueber, A., Schoeneberger, J., Wenzel, E., Havemann, K., Pies, A., Kneba, M., Edel, G., Pohl, S., Bulgay-Mörschel, M., Polzin, R., Issing, W., Clemm, Ch., Schorn, K., Ponta, H., Zöller, M., Hofmann, M., Arch, R., Heider, K. -H., Rudy, W., Tölg, C., Herrlich, P., Prümmer, O., Scherbaum, W. A., Porzsolt, F., Prümmer, O., Krüger, A., Schrezenmeier, H., Schlander, H., Pineo, G., Marin, P., Gluckman, E., Shahidi, N. T., Bacigalupo, A., Ratajczak, M. Z., Gewirtz, A. M., Ratei, R., Borner, K., Bank, U., Bühling, F., Reisbach, G., Bartke, L., Kempkes, B., Kostka, G., Ellwart, X., Birner, A., Bornkamm, G. W., Ullrich, A., Dörmer, P., Henze, G., Parwaresch, R., Müller-Weihrich, S. T., Klingebiel, Th., Odenwald, E., Brandhorst, D., Tsuruo, T., Wetter, O., Renner, C., Pohl, C., Sahin, U., Renner, U., Zeller, K. -P., Repp, R., Valerius, Th., Sendler, A., Kalden, J. R., PIatzer, E., Reuss-Borst, M. A., Bühring, H. J., Reuter, C., der Landwehr, II, U. Auf, der Landwehr, II, U. Auf, Schleyer, E., Rolf, C., Ridwelski, K., Matthias, M., Preiss, R., Riewald, M., Puzo, A., Serke, S., Rohrer, B., Pfeiffer, D., Hepp, H., Romanowski, R., Schött, C., Rüther, U., Rothe, B., Pöllmann, H., Nunnensiek, C., Schöllhammer, T., Ulshöfer, Th., Bader, H., Jipp, P., Müller, H. A. G., Rupp, W., Lüthgens, M., Eisenberger, F., Afflerbach, C., Höller, A., Schwamborn, J. S., Daus, H., Krämer, K., Pees, H., Salat, C., Reinhardt, B., Düll, T., Knabe, H., Hiller, E., Sawinski, K., Schalhorn, A., Kühl, M., Heil, K., Schardt, Ch., Drexler, H. G., Scharf, R. E., Suhijar, D., del Zoppo, G. J., Ruggeri, Z. M., Roll, T., Möhler, T., Giselinger, H., Knäbl, P., Kyrie, P. A., Lazcíka, K., Lechner, X., Scheulen, M. E., Beelen, D. W., Reithmayer, H., Daniels, R., Weiherich, A., Quabeck, K., Schaefer, U. W., Reinhardt J., Grimm M., Unterhalt M., Schliesser, G., Lohmeyer, J., Schlingheider, O., von Eiff, M., Schulze, F., Oehme, C., van de Loo, J., Schlögl E., Bemhart M., Schmeiser, Th., Rozdzinski, E., Kern, W., Reichle, A., Moritz, T., Merk, Bruno, Schmid, R. M., Perkins, N. D., Duckett, C. S., Leung, K., Nabel, G. J., Pawlaczyk-Peter, B., Kellermann-Kegreiß, Schmidt E., Steiert, I., Schmidt-Wolf, G., Schmidt-Wolf, I. G. H., Schlegel, P., Blume, K. G., Chao, N. J., Lefterova, P., Laser, J., Schmitz, G., Rothe, G., Schönfeld, S., Schulz, S., Nyce, J. W., Graf, N., Ludwig, R., Steinhauser, I., Brommer, A. E., Qui, H., Schroeder, M., Grote-Kiehn, J., Bückner, U., Rüger, I., Schröder, J., Meusers, P., Weimar, Ch., Schoch, C., Schröter, G., Stern, H., Buchwald, B., Schick, K., Avril, N., Flierdt, E. v. d., Langhammer, H. R., Pabst, H. W., Alvarado, M., Witte, T., Vogt, H., Schuler, U., Brammer, K., Klann, R. C., Schumm, M., Hahn, J., Günther, W., Wullich, B., Moringlane, J. R., Schöndorf, S., Schwartz, S., Bühring, H. -J., Notter, M., Böttcher, S., Martin, M., Schmid, H., Lübbe, A. S., Leib-Mösch C., Wankmüller, H., Eilbrück, D., Funke, I., Cardoso, M., Duranceyk, H., Seitz, R., Rappe, N., Kraus, H., Egbring, R., Haasberg, M., Havemann, K., Seibach, J., Wollscheid, Ursula, Serke, St., Zimmermann, R., Shirai, T., Umeda, M., Anno, S., Kosuge, T., Katoh, M., Moro, S., Su, C. -Y., Shikoshi, K., Arai, N., Schwieder, G., Silling-Engelhardt, G., Zühlsdorf, M., Aguion-Freire-Innig, E., van de Loo, J., Stockdreher, K., Gatsch, L., Tischler, H. -J., Ringe, B., Diedrich, H., Franzi, A., Kruse, E., Lück, R., Trenn, G., Sykora, J., Wen, T., Fung-Leung, W. P., Mak, T. W., Brady, G., Loke, S., Cossman, J., Gascoyne, R., Mak, T., Urasinski, I., Zdziarska, B., Usnarska-Zubkiewicz, L., Kotlarek-Haus, S., Sciborskl, R., Nowosad, H., Kummer, G., Schleucher, N., Preusser, P., Niebel, W., Achterrath, W., Pott, D., Eigler, F. -W., Venook, A., Stagg, R., Frye, J., Gordon, R., Ring, E., Verschuer, U. v., Baur, F., Heit, W., Corrons, J. L. L. Vives, Vogel, M., Nekarda, H., Remy, W., Bissery, M. C., Aapro, M., Buchwald-Pospiech, A., Kaltwasser, J. P., Jacobi, V., de Vos, Sven, Asano, Yoshinobu, Voss, Harald, Knuth, Alexander, Wiedemann, G., Komischke, B., Horisberger, R., Wussow, P. v., Wanders, L., Senekowitsch, R., Strohmeyer, S., Emmerich, B., Selbach, J., Gutensohn, K., Wacker-Backhaus, G., Winkeimann, M., Send, W., Rösche, J., Weide, R., Parviz, B., Havemann, K., Weidmann, B., Henss, H., Engelhardt, R., Bernards, P., Zeidler, D., Jägerbauer, E., Colajori, E., Kerpel-Fronius, S., Weiss, A., Buchheidt, D., Döring, A., D.Saeger, H., Weissbach, L., Emmler, J., Wermes, R., Meusers, P., Flasshove, M., Skorzec, M., Käding, J., Platow, S., Winkler, Ute, Thorpe, Philip, Winter, S. F., Minna, J. D., Nestor, P. J., Johnson, B. E., Gazdar, A. F., Havemann, K., Carbone, D. P., Wit, M. de, Bittner, S., Hossfeld, D., Wittmann, G., Borchelt, M., Steinhagen-Thiessen, E., Koch, K., Brosch, T., Haas, N., Wölfel, C., Knuth, A., Wölfel, T., Safford, M., Könemann, S., Zurlutter, K., Schreiber, K., Piechotka, K., Drescher, M., Toepker, S., Terstappen, L. W. M. M., Bullerdiek, J., Jox, A., zur Hausen, H., Wolters, B., Stenzinger, W., Woźny, T., Sawiński, K., Kozłowska-Skrzypczak, M., Wussow, P. v., Hochhaus, T., Ansarl, H., Prümmer, O., Zapf, H., Thorban, S., Präuer, H., Zeller, W., Stieglitz, J. v., Dürken, M., Greenshaw, C., Kabisch, H., Reuther, C., Knabbe, C., Lippman, M., Havemann, K., Wellstein, A., Degos, L., Castaigne, S., Fenaux, P., Chomienne, C., Raza, A., Preisler, H. D., PEG Interventional Antimicrobial Strategy Study Group, Interventional Antimicrobial Strategy Study Group of the Paul Ehrlich Society (PEG), and H. Riehm for the BFM study group

Published
1992
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26. Laser Metal Bonding (LMB) - low impact joining of thin aluminum foil to silicon and silicon nitride surfaces.

Author

John, Oliver, Paschen, Jan, De Rose, Angela, Steinhauser, Bernd, Emanuel, Gernot, Brand, Andreas A., and Nekarda, Jan

Abstract

We present the design, implementation and optimization of laser metal bonding (LMB), a new approach for joining thin aluminum foils and back surfaces of solar cells with a focus on low impact on the semiconductor and good adhesion. After gaining deep insights into laser-material interaction using finite difference simulations, we succeeded in establishing an expulsion free laser process that can be tuned from non-ablative bonding, which leaves the substrate largely intact, to welding, which produces highly adhesive joints. Experiments were conducted on a number of substrates, showing the correlation between damage and adhesion at different process parameters. [ABSTRACT FROM AUTHOR]

Published
2020
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27. Overcoming Throughput Limitations of Laser Systems in Solar Cell Manufacturing via On‐The‐Fly Processing Using Polygon Scanners

Author

Hoppe, Georg, Alvarez-Brito, Eduardo, Emanuel, Gernot, Nekarda, Jan, Diehl, Moritz, Preu, Ralf, and Meyer, Fabian

Abstract

In this paper, a high‐throughput on‐the‐fly laser processing system for the manufacture of silicon solar cells is proposed. Industrial laser processing machines are systematically limited in a trade‐off between throughput and focal spot size. Additionally, today's laser power and repetition rates cannot be fully utilized because of limited galvanometer scan speeds. This work aims to overcome this using a polygon scanner in an on‐the‐fly laser processing operation. Unlike conventional approaches, this setup does not use high‐precision positioning systems, but reduces wafer transport to a simple conveyor belt to optimize system cost, space, integrability, and cycle rate. The concept is implemented in a demonstrator setup. Applying a laser contact opening process, a throughput of 10 000 wafers per hour is demonstrated. A potential throughput of 13400 wafers per hour is calculated, considering the utilization of more powerful lasers. Inaccuracies due to the unevenness of the surface as well as transport speed oscillations are analyzed and shown not to have an impact on the efficiency of the cells processed with this setup. The throughput is increased five times compared to the theoretical upper‐throughput limitation for the same structure processed by a galvanometer‐driven laser system. The article proposes a high‐throughput on‐the‐fly laser processing system for making silicon solar cells. A demonstrator is presented, and its precision is characterized. The demonstrator is capable of performing a laser contact opening process at a throughput of 10 000 wph without losses in cell efficiency. It is about five times faster than traditional laser machines.

Published
2023
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31. Simplified Fabrication of n-type Cz-Si HIP-MWT+ Solar Cells with 20% Efficiency Using Laser Structuring.

Author

Lohmüller, Elmar, Werner, Sabrina, Maus, Stephan, Brand, Andreas, Jäger, Ulrich, Nekarda, Jan, and Clement, Florian

Abstract

We present 6-inch n-type Cz-Si metal wrap through (MWT) solar cells with screen-printed and fired contacts achieving energy conversion efficiencies of 20%. In order to decrease the occurrence of leakage currents under forward operation to a minimum after applying reverse bias load, the structuring of the rear side phosphorus doping in the area of the external p-type contacts is necessary. The fabrication of these so-called n-type high-performance MWT+ (n-HIP-MWT+) solar cells is considerably simplified by using laser processes to locally structure the rear side phosphorus doping. The n-HIP-MWT+ cells fabricated with laser structuring achieve the same peak energy conversion efficiency of 20% as conventionally fabricated ones, which are manufactured using an elaborate inkjet-based masking process prior to phosphorus diffusion. The loss of cell efficiency after reverse biasing is decreased to – 0.1% abs independent of the structuring method, and is three times smaller than the one observed for cells without structuring of the phosphorus doping. [ABSTRACT FROM AUTHOR]

Published
2016
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32. Novel Plating Processes for Silicon Heterojunction Solar Cell Metallization Using a Structured Seed Layer

Author

Glatthaar, Markus, Rohit, Rukmangada, Rodofili, Andreas, Snow, Yitzhak J., Nekarda, Jan, and Bartsch, Jonas

Abstract

We present metallization approaches for silicon heterojunction solar cells by plating onto a structured seed layer. Our approaches do not require expensive processing steps or consumables. The process starts with a full area deposition of a dielectric or alternatively a blanket metal layer such as Al onto indium tin oxide (ITO). Next, the grid-shaped seed layer is applied via printing or laser-transfer. An efficiency of 22.2% was obtained using a dielectric layer and laser-transfer, outperforming screen-printing by 0.4%. Applying Al instead of a dielectric has the advantage that the plating current spreads more homogeneously on the solar cell surface, which is of particular importance for plating on bifacial solar cells. For using an Al blanket layer on top of ITO and a grid-shaped seed layer, we developed a plating process that selectively plates on the seed layer and not on the Al layer.

Published
2017
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33. Easy Plating—A Simple Approach to Suppress Parasitically Metallized Areas in Front Side Ni/Cu Plated Crystalline Si Solar Cells

Author

Kluska, Sven, Buchler, Andreas, Bartsch, Jonas, Grubel, Benjamin, Brand, Andreas A., Gutscher, Simon, Cimiotti, Gisela, Nekarda, Jan, and Glatthaar, Markus

Abstract

Plated silicon solar cells with nonoptimized antireflective coatings (ARCs) may feature parasitic plating (PP), i.e., unwanted metal depositions in ARC defects/pinholes. The present work introduces the easy plating sequence that takes advantage of native oxide growth to avoid plating in unwanted ARC pinholes or defects due to the electrical insulation of these defects. This prevents PP for plated solar cells. Independent of the ARC pinhole density, an aesthetic immaculate appearance can be achieved using easy plating. It is shown that it is possible to gain up to 0.5 mA/cm2 in short-circuit current density and 6 mV in open-circuit voltage compared to the reference plating sequence at Fraunhofer ISE. The importance to avoid drawbacks in terms of contact resistance and contact adhesion due to laser-induced or native oxide at the Si-Ni interface in the easy plating sequence is discussed in detail and important influencing factors in the process chain are lined out. At this stage of development, low contact resistances are possible in some cases but further research is necessary to fully understand the impact of solar cell design and process-related influencing factors. Easy plating can be an option to avoid PP independent of prior ARC pinhole density.

Published
2017
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34. Selective Boron Emitters Using Laser-Induced Forward Transfer Versus Laser Doping From Borosilicate Glass

Author

Fernandez-Robledo, Susana, Kluska, Sven, Greulich, Johannes, and Nekarda, Jan

Abstract

Although highly doped boron selective emitters (SEs) can be formed by using laser doping (LD) from the borosilicate glass remaining after boron tribromide tube diffusion, the dopant concentration is limited. This limitation can be overcome by using a laser-induced forward transfer (DLIFT) approach. In this work, SEs formed by DLIFT and LD are compared to a homogenous tube diffusion (Diff) emitter. We investigated the correlation of the emitter saturation current density (j0e) and the specific contact resistance (ρc) with the sheet resistance (Rsheet) and the laser pulse energy density (Ep,d). For passivated emitters, j0e of DLIFT and LD emitters was around ten times higher than j0e of Diff emitters. For metallized emitters, simulated j0e of DLIFT emitters was lower than j0e of LD and Diff emitters for Rsheet glt; 40.0 Ω/sq. Moreover, we show how j0e can be further reduced by increasing the surface dopant concentration of the boron emitter and by reducing the laser-induced defects in the silicon crystal. Additionally, the metallization of DLIFT emitters with aluminum-silver paste by screen printing provided low contact resistances between metal and silicon (ρc <; 1.0 mΩ · cm2). Thus, p-type emitters can be optimized by forming an SE with the highly doped boron regions achieved by DLIFT under the screen-printed metallization.

Published
2017
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35. Comprehensive Simulation and Acceleration of the Foil-metallization Laser Process.

Author

Graf, Martin, Nekarda, Jan, Togny, Franciana Lazzarotto, Streek, André, Böhme, Rico, and Preu, Ralf

Abstract

The upgrade of state of the art p-type silicon solar cell production lines to passivated rear side technology (PERC) will be one of the major trends in the next years and new production processes for further cost reduction will continuously gain relevance. In 2007, we have introduced the laser based foil metallization technology “FolMet”: the rear electrode of p-type PERC devices as well as the local contact is fabricated by attaching conventional aluminum foil during the so-called laser fired contact process to the silicon wafer. This process features improved internal optical properties, a huge cost saving potential and a simplified cell production process. In this publication we focus on the acceleration of the laser process, which is together with module assembly issues a remaining challenge towards industrialization. We carried out comprehensive simulations, to better understand the correlation between different laser parameters on melting- and evaporation depth of the 8 μm thin aluminum foil. We determined lower limits for crucial laser pulse parameters to successfully attach the foil onto the substrate and validated these parameters experimentally. According to these results, we set up a system based on a pulsed high power laser featuring repetition rates F rep ≤ 2 MHz with an unique ultrafast polygon scanning system, allowing for scan-speeds v scan ≤ 1000 m/s. Thereby, we demonstrate processing times t pro < 0.8 s for industrial wafer, which corresponds to a reduction in laser process time by the factor of 20 compared to state of the art laser scanning technology. [ABSTRACT FROM AUTHOR]

Published
2015
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36. Fast Regeneration Processes to Avoid Light-Induced Degradation in Multicrystalline Silicon Solar Cells

Author

Krauss, Karin, Brand, Andreas A., Fertig, Fabian, Rein, Stefan, and Nekarda, Jan

Abstract

Light-induced degradation (LID) of multicrystalline silicon (mc-Si) solar cell performance has been reported to be surprisingly strong for conditions relevant under field operation. In paticular, solar cells with dielectrically passivated rear sides such as passivated emitter and rear cells are affected by this LID effect that can cause a loss of more than 10%rel in cell efficiency. With the root cause for the observed degradation being unknown to date, the underlying defect, however, has also been reported to be permanently deactivated under the same conditions at even longer time scales. However, a severe power loss due to the mc-Si specific LID is observed before the cells recover due to the long time scales of the regeneration under these conditions. Hence, regeneration on short time scales similar to the fast regeneration processes being reported for the boron-oxygen defect within p-type Czochralski-grown silicon is highly desirable also for p-type mc-Si, especially since mc-Si currently dominates industrial solar cell production. Within this work, partial regeneration of the defect causing the mc-Si specific LID is shown to be possible within less than 30 s, reducing the impact of LID by up to 60%, which leads to a significantly increased performance of the regenerated mc-Si solar cells.

Published
2016
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37. Passivation of Inline Wet Chemically Polished Surfaces for Industrial PERC Devices.

Author

Schwab, C., Wolf, A., Graf, M., Nekarda, J., Kästner, G., Zimmer, M., Kühnhold, S., Hofmann, M., Biro, D., and Preu, R.

Subjects
SURFACE passivation, IMPACT (Mechanics), METAL pickling, THERMAL oxidation (Materials science), SOLAR cell efficiency, QUANTUM efficiency, SURFACE area
Abstract

Abstract: We study the impact of the residual surface morphology resulting from rear side wet chemical polishing of initially random pyramid textured surfaces on large area industrial rear surface thermal oxide passivated Cz Si solar cells. Cell parameters for three different surfaces (low, medium and high removal of Si) and a fully textured rear surface as reference are presented for solar cells with rear sides metallized either by physical vapour deposition or by screen printing technique. For both metallization schemes a flattened surface clearly results in higher values for open circuit voltage and short circuit current density and thus also cell efficiency. Median efficiencies up to 19.4% (239cm2, as processed) and stabilized peak efficiency of 19.3% (confirmed by Fraunhofer ISE CalLab) are reached. Carrier lifetime and quantum efficiency measurements confirm that the rear surface recombination and injection dependence strongly reduces for flattened surfaces, which is attributed to changes in crystal orientation and reduced surface area. [Copyright &y& Elsevier]

Published
2012
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38. Recombination on Locally Processed Wafer Surfaces.

Author

Saint-Cast, P., Nekarda, J., Hofmann, M., Kuehnhold, S., and Preu, R.

Subjects
SILICON wafers, SURFACES (Technology), LOGICAL prediction, MATHEMATICAL models, SEPARATION (Technology), POINT defects
Abstract

Abstract: This paper is revisiting the problem of recombination on locally processed area (contacts, local doping …), based on the concept of point recombination rate (pLPA). The newly introduced effective point recombination rate (peff) can be easily determined from the effective surface recombination velocity. It also allows predictions and comparisons in most of the practical cases. Further analysis allows the separation of the influence of pLPA from the one of the transport of the carrier in a transparent way. Due to its simplicity, transparency and accuracy, the model proposed here is believed to be more suitable to recent local processing technology than the existing analytical models. [Copyright &y& Elsevier]

Published
2012
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39. Challenges and advances in back-side metallization.

Author

Preu, Ralf, Wolf, Andreas, Hofmann, Marc, Clement, Florian, Nekarda, Jan, Rentsch, Jochen, and Biro, Daniel

Subjects
SEMICONDUCTOR wafers, SEMICONDUCTORS, MICROELECTRONICS, SOLAR cells, PHOTOVOLTAIC cells, PHOTOELECTRIC cells, SOLAR energy
Abstract

In today's market, crystalline silicon wafer technology dominates industrial solar cell production. Common devices feature opposing electrodes that are situated at the front and rear surface of the wafer and subsequent front-to-rear interconnection is used for module assembly. This paper reflects the functions which have to be fulfilled for the backside contact of the solar cell as well as challenges and advances for the two basic classes: full-area and local rear contact formation. While full-area contacting has proven to be a reliable technology for industrial production, local contacting through dielectric layers has yet to be put through its paces in industrial implementation. [ABSTRACT FROM AUTHOR]

Published
2010

40. Microarray-Based Prediction of Tumor Response to Neoadjuvant Radiochemotherapy of Patients With Locally Advanced Rectal Cancer.

Author

Rimkus, Caroline, Friederichs, Jan, Boulesteix, Anne–laure, Theisen, Jörg, Mages, Jörg, Becker, Karen, Nekarda, Hjalmar, Rosenberg, Robert, Janssen, Klaus–Peter, and Siewert, Jörg Rüdiger

Subjects
CANCER patients, CANCER, CANCER education, GENES
Abstract

Background & Aims: Neoadjuvant chemoradiotherapy has become a standard treatment of locally advanced rectal carcinomas, even though the responsiveness varies from complete response to resistance. The aim of the study was to evaluate the capacity of gene expression signatures to identify responders and nonresponders pretherapeutically. Methods: By using microarray technology we generated gene expression profiles of 43 biopsy specimens of locally advanced rectal carcinomas. The transcription profile then was compared with histopathologic response and used to identify a set of genes discriminating responders from nonresponders. Results: We identified a gene expression signature of 42 genes, mostly encoding proteins that either play a role in the nucleus, such as the transcription factor ETS2, or are associated with transport function, such as the solute carrier SLC35E1, or the regulation of apoptosis, such as caspase-1. In leave-one-out cross-validation the correct classification of a responder was 71%, the specificity of the analysis for a correct classification of a nonresponder was 86%. By applying an additional statistical method of 200 successive splittings into training and test data sets we generated an individual prediction accuracy measure for each predicted response. Conclusions: Our study shows that pretherapeutic prediction of response of rectal carcinomas to neoadjuvant chemoradiotherapy is feasible, and may represent a new valuable and practical tool of therapeutic stratification. [Copyright &y& Elsevier]

Published
2008
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41. Serotonin Excites Neurons in the Human Submucous Plexus via 5-HT3 Receptors.

Author

Michel, Klaus, Zeller, Florian, Langer, Rupert, Nekarda, Hjalmar, Kruger, Dagmar, Dover, Terri J., Brady, Catherine A., Barnes, Nicholas M., and Schemann, Michael

Subjects
SEROTONIN, NEUROTRANSMITTERS, TRYPTAMINE, PATIENTS
Abstract

Background & Aims: Serotonin (5-hydroxytryptamine [5-HT]) is a key signaling molecule in the gut. Recently, the neural 5-HT3 receptor received a lot of attention as a possible target in functional bowel diseases. Yet, the 5-HT3 receptor–mediated changes in properties of human enteric neurons is unknown. Methods: We used a fast imaging technique in combination with the potentiometric dye 1-(3-sulfonatopropyl)-4-[β[2-(di-n-octylamino)-6-naphthyl]vinyl]pyridinium betaine to monitor directly the membrane potential changes in neurons of human submucous plexus from surgical specimens of 21 patients. An Ussing chamber technique was used to study 5-HT3 receptor involvement in chloride secretion. Results: Local microejection of 5-HT directly onto ganglion cells resulted in a transient excitation of enteric neurons characterized by increased spike discharge. This response was mimicked by the 5-HT3 receptor agonist, 2-methyl-5-HT, and blocked by the 5-HT3 receptor antagonist, tropisetron. The proportions of 5-HT–responsive nerve cells per ganglion ranged from 25.5% ± 18.4% in the duodenum to 54.2% ± 46.9% in the colon. Interestingly, 2-methyl-5-HT did not evoke chloride secretion in the human intestine but it did in the guinea-pig intestine. Specific 5-HT3A and 5-HT3B receptor subunit immunoreactivity as well as 5-HT3A and 5-HT3B receptor–specific messenger RNA were detected in the tissue samples. Based on co-labeling with the pan-neuronal marker HuC/D we conclude that submucous nerve cells potentially express heteromeric 5-HT3A/B receptors. Conclusions: We show that 5-HT excited human enteric neurons via 5-HT3 receptors, which may comprise both 5-HT3A and 5-HT3B receptor subunits. [Copyright &y& Elsevier]

Published
2005
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42. Investigation of the Defect Distribution of Laser Contact Opening Applied to Poly‐Si/SiNxStacks

Author

Steinhauser, Bernd, Arya, Varun, Jakob, Leonie, Heinz, Friedemann D., Schmiga, Christian, Grübel, Benjamin, Brand, Andreas A., Kluska, Sven, and Nekarda, Jan F.

Abstract

Herein, an analysis on the impact of laser contact opening of TOPCon/SiNxstacks is presented. By etching in tetramethylammonium hydroxide (TMAH), the defect distribution in the interfacial tunnel oxide is accessed and analyzed. The defect density is significantly increased in areas where adjacent laser contact openings (LCO) overlap. Using microscopic photoluminescence (μ‐PL) spectroscopy, it is verified that correlates with an increase in the local recombination rate and thus an increase in the J0,Met. Therefore, overlapping LCO of SiNxin TOPCon/SiNxstacks should be avoided as much as possible. Furthermore, the investigations indicate that defects in the interfacial oxide are dominantly created along exposed structures like tips and edges of (etched‐back) pyramids. A comparison of TOPCon/SiNx stacks with a variation of TOPCon thicknesses indicate that etch pits, and thus the defect density, related to LCO become more significant at lower thicknesses. For poly‐Si contact schemes, an intact interfacial oxide is crucial. Using a tetramethylammonium hydroxide (TMAH) etch, the defects in the oxide due to laser ablation of SiNxon poly‐Si are magnified. The defect density is significantly increased in areas where adjacent laser pulses overlap. According to μPL, this correlates with an increase in the local recombination rate and thus J0,Met.

Published
2022
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43. Industry Evidence on the Effects of Government Spending

Author

Nekarda, Christopher J and Ramey, Valerie A

Abstract

AbstractThis paper investigates the effects of government purchases at the industry level in order to shed light on the transmission mechanism for government spending on the aggregate economy. We create a new panel dataset that matches output and labor variables to industry-specific shifts in government demand. An increase in government demand raises output and hours, lowers real product wages and labor productivity, and has no effect on the markup. The estimates also imply approximately constant returns to scale. The findings are more consistent with the effects of government spending in the neoclassical model than the textbook New Keynesian model. (JEL E12, E23, E62, H50)

Published
2011
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44. Comparison of two density gradient centrifugation systems for the enrichment of disseminated tumor cells in blood

Author

Rosenberg, R., Gertler, R., Friederichs, J., Fuehrer, K., Dahm, M., Phelps, R., Thorban, S., Nekarda, H., and Siewert, J. R.

Abstract

The detection of disseminated tumor cells in peripheral blood is limited by the presence of very few tumor cells within a large number of blood cells. Therefore, tumor cell detection calls for enrichment systems with effective depletion of blood cells and high tumor cell recovery. We compared the new density gradient centrifugation method OncoQuick with the standard method of Ficoll. The enriched cell fractions were quantified. Tumor cell spiking experiments examined the recovery of tumor cells as detected by immunocytochemistry and cytokeratin-20 reverse transcriptase–polymerase chain reaction (RT-PCR). Clinical application of OncoQuick was evaluated in 37 peripheral blood samples of patients with gastrointestinal carcinomas. The depletion of mononuclear cells (MNCs) in the enriched cell fraction after OncoQuick centrifugation was 632-fold, with an average cell number of 9.5 × 104, compared with Ficoll, with a depletion factor of 3.8 and a mean number of 1.6 × 107 MNCs. The mean tumor cell recovery rates were 87% for OncoQuick and 84% for Ficoll. The increased depletion of MNCs with OncoQuick centrifugation further simplified immunocytochemical evaluation by reducing the number of cytospins and increasing the tumor cell density. Due to the reduced number of co-enriched MNCs by OncoQuick, the blood volume, which could be analyzed in one RT-PCR reaction, was increased up to 30 ml. Examination of peripheral blood samples from 37 patients with gastrointestinal tumors showed a cytokeratin-20 detection rate of 30% and a significant correlation with the presence of distant metastases (P &lt; 0.02). OncoQuick significantly reduced the co-enriched number of MNCs, with a high tumor cell recovery rate. Processing blood from tumor patients with OncoQuick increased the chance of detecting circulating tumor cells. Cytometry 49:150–158, 2002. © 2002 Wiley-Liss, Inc.

Published
2002
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45. Prognostic potential of the telomerase subunit human telomerase reverse transcriptase in tumor tissue and nontumorous mucosa from patients with colorectal carcinoma

Author

Gertler, Ralf, Rosenberg, Robert, Stricker, Dominik, Werner, Martin, Lassmann, Silke, Ulm, Kurt, Nekarda, Hjalmar, and Siewert, Joerg-Ruediger

Abstract

The stabilization of telomere lengths by telomerase activation is an important step in carcinogenesis and cell immortalization. Human telomerase reverse transcriptase (hTERT) is the catalytic subunit of this enzyme. The objective of this study was to evaluate the use of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for the quantification of hTERT in tumor and nontumorous tissue samples. Matched samples of tumor and adjacent nontumorous mucosa samples from 57 patients with completely resected colorectal carcinoma (International Union Against Cancer Stage I–IV) who underwent complete resection (R0) were quantified for hTERT mRNA expression using real-time RT-PCR. The expression levels were correlated with histopathologic findings and with survival. The median follow-up was 76 months. hTERT mRNA was expressed in all tumor samples and in all samples of adjacent mucosa. In 12 patients (21%), there was higher hTERT expression in tumor samples compared with nontumorous samples. Compared with tumor samples, the expression of hTERT in samples of nontumorous mucosa decreased with age (P = 0.06). hTERT mRNA expression in both tumor tissue and adjacent mucosa was correlated significantly with the histologic grade of colorectal carcinoma (P &lt; 0.04 and P &lt; 0.05, respectively). Patients with hTERT expression in tumor tissue in relation to the adjacent mucosa of > 0.57 had a significantly poorer overall survival compared with patients with lower hTERT ratios (P &lt; 0.02). In addition to the established prognostic factor lymphatic vessel invasion, the hTERT ratio proved to be of independent prognostic value (P &lt; 0.05). The prognostic potential of hTERT in patients with colorectal carcinoma and the correlation of hTERT with tumor grade underlines the role of hTERT as a molecular marker for biologic tumor staging. Cancer 2002;95:2103–11. © 2002 American Cancer Society. DOI 10.1002/cncr.10939

Published
2002
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46. Functional loss of E‐cadherin and cadherin‐11 alleles on chromosome 16q22 in colonic cancer

Author

Braungart, Evelyn, Schumacher, Christoph, Hartmann, Elke, Nekarda, Hjalmar, Becker, Karl‐Friedrich, Höfler, Heinz, and Atkinson, Michael J.

Abstract

Proteins of the cadherin family regulate cellular adhesion and motility and are believed to act as tumour suppressors. Previous studies have identified frequent mutation and allelic inactivation of the E‐cadherin (cadherin‐1) locus in diffuse gastric cancer. At least two other cadherin genes, P‐cadherin (cadherin‐3) and OB‐cadherin (cadherin‐11), have been mapped close to the E‐cadherin gene on chromosome 16q22. As this region of the genome is frequently deleted in malignancy, multiple cadherin loci may be affected by losses of chromosome 16q22. The expression of mRNA transcripts from polymorphic alleles of the E‐cadherin and cadherin‐11 genes was examined in 30 cases of colonic, gastric, and renal carcinoma. In gastric cancer, loss of expression of one allele was restricted to the E‐cadherin locus, whilst in renal carcinoma neither locus was affected. In colonic cancers, loss of expression of one E‐cadherin allele was detected in 5 of 22 cases, whilst loss of a cadherin‐11 allele was seen in 5 of 23 cases. This functional loss of cadherin gene expression may be due to gene deletion, inactivation or recombination. As no evidence of cadherin gene mutation was observed in the remaining transcripts, we can conclude that these two genes are only indirectly involved in the pathogenesis of colorectal cancer. Copyright © 1999 John Wiley & Sons, Ltd.

Published
1999
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47. Laser Ablation and Ni/Cu Plating Approach for Tunnel Oxide Passivated Contacts Solar Cells with Variate Polysilicon Layer Thickness: Gains and Possibilities in Comparison to Screen Printing

Author

Arya, Varun, Steinhauser, Bernd, Gruebel, Benjamin, Schmiga, Christian, Bay, Norbert, Brunner, Damian, Passig, Michael, Brand, Andreas A., Kluska, Sven, and Nekarda, Jan

Abstract

Herein, an alternative approach of metallization on tunnel oxide passivated contacts (TOPCon) devices, through the method of localized laser ablation and nickel–copper plating, is presented. The method is demonstrated to be a viable and effective alternative, yielding better performance and results than the conventional screen‐printed contacts. The laser ablation process, with a lower increase in recombination current as compared to screen printing, proves to be a far less damaging process than the latter. TOPCon solar cells, fabricated and compared using the two metallization approaches, show a substantial improvement in an absolute power efficiency of ≈1%. Due to the highly superficial nature of damage with the optimized laser parameters, it enables the reduction of the poly‐Si layer thickness down to 70 nm in the TOPCon stack and also a high cell conversion efficiency of 22%. This allows for a substantial reduction in ownership costs of the final device without compromising on performance, making TOPCon cells with plated contacts an attractive technological upgrade for industrial‐level production following the passivated emitter rear contact cell technology. Latest investigation of laser interaction on passivated contact devices such as TOPCon, to form nickel/copper plated contacts, reveal interesting findings. With optimized wavelength and pulse duration, damage from laser is kept highly superficial and is reversible by thermal annealing process. This allows reducing the polysilicon thickness, thereby decreasing production costs and also enables an efficiency gain of 1% (absolute).

Published
2020
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