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4. Study of bulk carrier properties in largely hybridized InAsSb/GaSb superlattice materials.

Author

Haugan, H. J., Elhamri, S., Mahalingam, K., Das, D., Ram-Mohan, L. R., Bedford, R. G., and Eyink, K. G.

Subjects
INTERFACIAL roughness, ELECTRON density, CHARGE carrier mobility, WAVE functions, LOW temperatures, SUPERLATTICES
Abstract

The prospect of implementing quantum device architectures with technologically mature III–V semiconductors requires precisely controlled topologically protected edge states and bulk insulation. However, experimentally reaching this regime with III–V heterostructure epitaxy has been difficult due to charged bulk defects. Charged defects prevent bulk insulation and disturb the stability of edge states. Hence, we study carrier properties in a hybridized III–V InAs0.9Sb0.1/GaSb superlattice (SL) structure. We realize that an electron density (mobility) is limited to approximately 1012 cm−2 (104 cm2/V s). In order to understand these limits, the authors investigate the in-plane mobility of hybridized SLs as a function of current-carrying layer thickness, L, to determine scattering mechanisms that restrict carrier mobility. Although theory predicts the in-plane mobility is proportional to L6 dominated by interface roughness scattering (IRS) at low temperatures, we report that mobility follows the fourth power dependence, which is a weaker than expected from IRS theory. We attribute the discrepancy between experiment and the model to interface intermixing and wave function penetration into barrier regions. We use this understanding to develop a strategy for realizing high-performance topological materials. [ABSTRACT FROM AUTHOR]

Published
2023
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6. Rationale and protocol of the ENGAGE study: a double-blind randomized controlled preference trial using a comprehensive cohort design to measure the effect of a cognitive and leisure-based intervention in older adults with a memory complaint

Author

Belleville, S., Moussard, A., Ansaldo, A. I., Belchior, P., Bherer, L., Bier, N., Bohbot, V. D., Bruneau, M.-A., Cuddy, L. L., Gilbert, B., Jokel, R., Mahalingam, K., McGilton, K., Murphy, K. J., Naglie, G., Rochon, E., Troyer, A. K., and Anderson, N. D.

Published
2019
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8. Design and growth of short-period long wavelength infrared InAsSb/InAsSb superlattices on lattice engineered metamorphic buffers.

Author

Haugan, H. J., Ciani, A. J., Grein, C. H., and Mahalingam, K.

Subjects
SUPERLATTICES, HOLE mobility, LATTICE constants, BUFFER layers, LIGHT absorption, WAVELENGTHS, ULTRACOLD molecules
Abstract

There has been steady effort to advance Ga-free InAs1−xSbx/InAs1−ySby superlattice (SL) materials for long-wavelength infrared (LWIR) detector applications. Although Ga-free SLs grown pseudomorphically on GaSb wafers work well in mid-wavelength applications, most LWIR Ga-free SL designs suffer from relatively low optical absorption and poor hole transport. One of the main problems in using the Ga-free material system for LWIR applications is a tremendous constraint on band engineering imposed by matching the SL lattice parameter to the lattice constant of conventional GaSb substrates. In this work, we propose several lattice engineered short-period LWIR InAs1−xSbx/InAs1−ySby SL designs that can enhance optical absorption and vertical hole mobility at an 11 μm cutoff wavelength. We also performed test growths of the designed structures on lattice-matched homogeneous buffer layers on GaAs wafers. [ABSTRACT FROM AUTHOR]

Published
2020
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14. Growth of short-period lnAs/GaSb superlattices

Author

Haugan, H.J., Mahalingam, K., Brown, G.J., Mitchel, W.C., Ullrich, B, Elhamri, S., Grazulis, L., Wickett, J.C., and Stokes, D.W.

Subjects
Transmission electron microscopes -- Usage, Gallium compounds -- Thermal properties, Superlattices as materials -- Analysis, Physics
Abstract

The technique of transmission electron microscopy is used to study the growth and morphological properties of several short-period InAs/GaSb supperlattices (SLs), which exhibit large intervalance band separations, making room temperature operations possible. The analysis shows that the structural degradation of the SLs progresses and intensifies with the increase in the period, as SLs with extremely thin periods can also be obtained by using slower growth rates.

Published
2006

24. Sylvester o’halloran surgical scientific meeting: Proceedings of meeting held 6th & 7th March 1998 in the Foundation Building, University of Limerick

Author

Relihan, N., McGreal, G., Murray, M., McDermott, E. W., O’Higgins, N. J., Duffy, M. J., McNamara, D. A., Harmey, J., Wang, J. H., Donovan, D., Walsh, T. N., Bouchier-Hayes, D. J., Kay, E., Kelly, J. D., Weir, H. P., Keane, P. F., Johnston, S. R., Williamson, K. E., Hamilton, P. W., McManus, D., Morrin, M., Delaney, P. V., Winter, D. C., Harvey, B. J., Geibel, J. P., O’Sullivan, G. C., Delaney, C. P., Coffey, R., Gorey, T. F., Fitzpatrick, J. M., Fanning, N. F., Kirwan, W., Cotter, T., Bouchier-Hayes, D., Redmond, H. P., McNamara, D. A., Pidgeon, G., Harmey, J., Walsh, T. N., Bouchier-Hayes, D. J., Redmond, H. P., Fennessy, F., Wang, J. H., Kelly, C., Bouchier-Hayes, D., Delaney, C. P., Flavin, R., Coffey, R., Gorey, T. F., Fitzpatrick, J. M., Rasheed, A. M., Wang, J. H., Kelly, C., Bouchier-Hayes, D. J., Leahy, A., Lang, E. E., Caldwell, M. T. P., Tanner, W. A., Kiely, P. D., O’Reilly, M., Tierney, S., Barry, M., Delaney, P. V., Drumm, J., Grace, P. A., Gallagher, C. M., Grant, D. C., Connell, P., Barry, M. K., Traynor, O., Hyland, J. M. P., O’Sullivan, M. J., Evoy, D., Redmond, H. P., Kirwan, W. O., Cannon, B., Kenny-Walshe, L., Whelton, M. J., O’Grady, H., O’Neill, S., Grant, D. C., Barry, M. K., Traynor, O., Hyland, J. M., Teh, S. H., O’Ceallaigh, S., O’Donohoe, M. K., Tanner, W. A., Keane, F. B., O’Toole, G. C., Grant, D. C., Barry, M. K., Hyland, J. M. P., Calleary, J., Basso, L., Amjad, S. B., Khan, Z., McMullin, L., Joyce, W. P., Balfe, P. J., Caldwell, M. T., Keane, F. B., Tanner, W. A., Teahan, S., Al-Brekeit, K., Tierney, S., Rasheed, A., Bouchier-Hayes, D., Leahy, A., O’Neill, S., Delaney, C. P., Gorey, T. F., Fitzpatrick, J. M., Cullen, A., O’Keane, C., Fennessy, F., Kelly, C., Bouchier-Hayes, D., Fennessy, F., Wang, J. H., Kelly, C., Bouchier-Hayes, D. J., Winter, D. C., MacFarlane, J., Harvey, B. J., O’Sullivan, G. C., Walsh, M., McGloughlin, T., Grace, P., Colgan, D., Madhavan, P., Sultan, S., Colgan, M. P., Moore, D., Shanik, G., McEniff, N., Molloy, M., Eguare, E., Fiuza, C., Grace, P., Burke, P., Maher, R., Creamer, M., Cronin, C. J., Sigurdsso, H. H., Kim, W., Linklater, G., Cross, K. S., Simpson, W. G., Shaw, J. A. M., Pearson, D. W. M., Fitzgerald, P., Quinn, P., Tierney, S., Bouchier-Hayes, D., Brady, C. M., Shah, S. M. A., Ehtisham, M., Khan, M. S., Flood, H. D., Loubani, M., Sweeney, K., Lenehan, B., Lynch, V., Joy, A., McGreal, G., Reidy, D., Mahalingam, K., Cashman, W., Mulligan, E. D., Purcell, T., Dunne, B., Griffin, M., Noonan, N., Hollywood, D., Keeling, N., Reynolds, J. V., Hennessy, T. P. J., O’Halloran, D., McGreal, G., McDermott, E. W., O’Higgins, N. J., Neary, P., Hamilton, D., Haider, N., Aherne, N., Watson, R. G. K., Walsh, D., Murphy, M., Joyce, M., Johnston, S., Clinton, O., Given, H. F., Brannigan, A., O’Donohoe, M., Donohoe, J., Corrigan, T., Bresnihan, M., O’Donohoe, M. K., Feeley, T. M., Sultan, S., Madhavan, P., Colgan, M. P., Moore, D., Shanik, G., McMonagle, M. P., Quinlan, D., Kelly, D., Hegarty, P. K., Tan, B., Cronin, C., Brady, M. P., Zeeshan, M., McAvinchey, D. J., Aherne, N., Mooney, C., Coyle, D., Haider, N., Hamilton, D., Neary, P., Watson, R. G. K., Khayyat, G., Masterson, E., Thambi-Pillai, T., Farah, K., Delaney, C. P., Codd, M. B., Fitzpatrick, J. M., Gorey, T. F., Barry, M. K., Tsiotos, G. G., Johnson, C. D., Sarr, M. G., Kell, M. R., Lynch, M., Ryan, D., O’Donovan, A., Winter, D. C., Redmond, H. P., Delaney, C. P., Cassidy, M., Doyle, M., Fulton, G., O’Connell, P. R., Kingston, R., Dillon, M., Barry, M., Tierney, S., Grace, P. A., McGreal, G., Lenehan, B., Murray, M., McDermott, E., O’Higgins, N., Kell, M. R., O’Sullivan, R. G., Tan, B., and O’Donnell, J. A.

Published
1998
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26. Watson–Crick Jumping Finite Automata: Combination, Comparison and Closure.

Author

Mishra, U K, Mahalingam, K, and Rama, R

Subjects
*FINITE state machines
Abstract

A new model of computation called Watson–Crick jumping finite automata was introduced by Mahalingam et al. , and the authors study the computing power and closure properties of the variants of the model. There are four variants of the model: no state, 1-limited, all-final and simple Watson–Crick jumping finite automata. In this paper, we introduce a restricted version that is a combination of variants of the existing model. It becomes essential to explore the computing power and closure properties of these combinations. The combination variants are extensively compared with Chomsky hierarchy, general jumping finite automata family and among themselves. We also explore the closure properties of such restricted automata. [ABSTRACT FROM AUTHOR]

Published
2022
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36. Arsenic cluster dynamics in doped GaAs

Author

Melloch, M.R., Otsuka, N., Mahalingam, K., Chang, C.L., Woodall, J.M., Pettit, G.D., Kirchner, P.D., Cardone, F., Warren, A.C., and Nolte, D.D.

Subjects
Gallium arsenide semiconductors -- Research, Arsenic -- Research, Semiconductor doping -- Research, Physics
Abstract

A study was done on arsenic cluster dynamics in doped GaAs. Results show a preferential growth of As precipitates on the n side of GaAs pn junctions which increases with the progress of the coarsening process. In addition, the pn junction depletion region becomes free of As precipitates. A stable Be profile results from the excess As even to anneals of 950 degrees Centigrade. The study also showed a temperature cycling technique for growing arbitrarily thick GaAs epilayers containing As precipitates.

Published
1992

42. Relative Watson-Crick Primitivity of Words

Author

Kari, L., Manasi S. Kulkarni, and Mahalingam, K.

Subjects
Computer Science::Computation and Language (Computational Linguistics and Natural Language and Speech Processing), Computer Science::Formal Languages and Automata Theory, MathematicsofComputing_DISCRETEMATHEMATICS
Abstract

We introduce the concept of relative Watson-Crick primitivity of words and its generalization, the relative theta-primitivity of words, where theta is a morphic or an antimorphic involution. Similar to relatively prime integers which do not share any common factors, we call two words u and v relatively theta-primitive if they do not share a common theta-primitive root. We study some combinatorial properties of relatively theta-primitive words, as well as establish relations between each of the two words u and v and the result of some binary word operation between u and v, from this perspective., Journal of Automata, Languages and Combinatorics, Volume 23, Numbers 1-3, 2018, 201-217

Published
2018
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43. Tuning Perpendicular Magnetic Anisotropy by Oxygen Octahedral Rotations in (La1-xSrxMnO3)/ (SrIrO3) Superlattices

Author

Yi, D, Flint, CL, Balakrishnan, PP, Mahalingam, K, Urwin, B, Vailionis, A, N'Diaye, AT, Shafer, P, Arenholz, E, Choi, Y, Stone, KH, Chu, JH, Howe, BM, Liu, J, Fisher, IR, and Suzuki, Y

Abstract

© 2017 American Physical Society. American Physical Society. Perpendicular magnetic anisotropy (PMA) plays a critical role in the development of spintronics, thereby demanding new strategies to control PMA. Here we demonstrate a conceptually new type of interface induced PMA that is controlled by oxygen octahedral rotation. In superlattices comprised of La1-xSrxMnO3and SrIrO3, we find that all superlattices (0≤x≤1) exhibit ferromagnetism despite the fact that La1-xSrxMnO3is antiferromagnetic for x>0.5. PMA as high as 4×106 erg/cm3 is observed by increasing x and attributed to a decrease of oxygen octahedral rotation at interfaces. We also demonstrate that oxygen octahedral deformation cannot explain the trend in PMA. These results reveal a new degree of freedom to control PMA, enabling discovery of emergent magnetic textures and topological phenomena.

Published
2017
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45. Growth of short-period InAs/GaSb superc.

Author

Haugan, H. J., Mahalingam, K., Brown, G. J., Mitchel, W. C., Ullrich, B., Grazulis, L., Elhamri, S., Wickett, J. C., and Stokes, D. W.

Subjects
*SUPERLATTICES, *INDIUM arsenide, *THIN films, *STRUCTURAL dynamics, *TRANSMISSION electron microscopy, *PHOTOLUMINESCENCE
Abstract

The purpose of this work is to explore materials for midinfrared detectors that can operate at room temperature. Shorter-period InAs/GaSb superlattices (SLs) have larger intervalance band separations, which are beneficial for reducing Auger recombination and tunneling current, thus making room temperature operation possible. To test these possibilities, several short-period SLs ranging from 50 to 11 Å were grown and their morphological properties were carefully monitored by transmission electron microscopy. The effect of structural degradation caused by the period reduction on the optical properties was studied using low-temperature photoluminescence (PL). The samples with larger periods (50–32 Å) showed excellent structural qualities and produced narrow full width at half maximum (FWHM) of the PL peak (5 meV). As the period approached 24 Å, slight layer thickness undulations within the SLs were observed and these undulations intensified as the period further reduced to 17 Å. These structural degradations strongly influence optical properties causing significant broadening in the FWHM and higher residual carrier concentration in the shorter-period SLs. With slower growth rates, samples with periods as thin as 19 Å were grown without significant layer undulations. [ABSTRACT FROM AUTHOR]

Published
2006
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46. Band gap tuning of InAs/GaSb type-II superlattices for mid-infrared detection.

Author

Haugan, H. J., F. Szmulowicz, Brown, G. J., and Mahalingam, K.

Subjects
INDIUM arsenide, GALLIUM, SUPERLATTICES, INFRARED detectors, MOLECULAR beam epitaxy, CRYSTAL growth
Abstract

The superlattice (SL) of a 40 period InAs/GaSb SL structure were varied around the 20.5 Å InAs/24 Å GaSb design in order to produce a device with an optimum mid-infrared photoresponse and a sharpest photoresponse cutoff. The samples for this study were grown by molecular beam epitaxy with precisely calibrated growth rates. Varying individual layer width around the nominal design, we were able to systematically change the photoresponse cutoff wavelength between 4.36 to 3.45 um by decreasing the InAs width from 23.5 to 17.5 Å, and between 4.55 to 4.03 μm by increasing the GaSb width from 18 to 27 Å. Therefore, the cutoff changes faster with decreasing InAs rather than increasing GaSb width. However, increasing GaSb width more effectively enhances the sharpness of photoresponse near band edge. The effect of design parameters on the photoresponse cutoff and other effects are explained by a nonperturbative, modified envelope function approximation (EFA) calculation that includes the interface coupling of heavy, light, and spin-orbit holes resulting from the in-plane asymmetry at InAs/GaSb interfaces. Using the modified EFA model, the SL design at fixed period of 44.5 Å was adjusted for the optimum performance. [ABSTRACT FROM AUTHOR]

Published
2004
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50. High quality factor integrated gigahertz magnetic transformers with FeGaB/Al2O3 multilayer films for radio frequency integrated circuits applications.

Author

Gao, Y., Zare, S., Yang, X., Nan, T. X., Zhou, Z. Y., Onabajo, M., O'Brien, Kevin P., Jalan, Umesh, EI-tatani, Mohammed, Fisher, Paul, Liu, M., Aronow, A., Mahalingam, K., Howe, B. M., Brown, G. J., and Sun, N. X.

Subjects
INTEGRATED circuits, REDUCED instruction set computers, ELECTRONIC circuits, THIN films, ELECTRONICS
Abstract

This work report new integrated high quality factor (Q) GHz magnetic transformers based on solenoid structures with FeGaB/Al2O3 multilayer films. These transformers show excellent high-frequency performance with a wide operation frequency range of 0.5-5GHz, in which primary, secondary, and mutual inductances are flat, and the peak quality factor can reach around 14 at frequency of 1.2 GHz. High mutual coupling and low insertion loss are also demonstrated. These novel GHz transformers with high Q and mutual coupling show great promise for applications in radio frequency integrated circuits. [ABSTRACT FROM AUTHOR]

Published
2014
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