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Hintergrund: Es gibt bislang keine deutschlandweite epidemiologische Untersuchung zu Speicheldrusenoperationen. Methoden: Die bundesweite Diagnosis-Related Groups (DRG)-Statistik der Jahre 2007–2011 wurde ausgewertet hinsichtlich der Indikationen auf Basis der ICD-10-Codes. Es wurde Operationsraten pro 100 000 Personenjahre fur beide Geschlechter und in Alterskohorten berechnet. Ergebnisse: Die durchschnittlichen deutschlandweiten stationaren Operationsraten 2007–2011 betrugen fur Inzisionen an den Speicheldrusen (OPS-Ziffer 5–260) 1,43 pro 100 000 Personen, fur Exzisionen an den Speicheldrusen (5–261) 2,06 pro 100 000, fur Speicheldrusenresektionen (5–262) 16,15 pro 100 000 und fur ausere Inzisionen an den Speicheldrusen (5–270) 0,43 pro 100 000. Fur die genannten vier OPS-Ziffern betrugen die Operationsraten in absteigender Haufigkeit fur gutartige Tumoren 10,08 pro 100 000, fur Speicheldrusenentzundungen (ohne Speichelsteine) 4,00 pro 100 000, fur Speicheldrusenmalignome 3,90 pro 100 000, und fur Speichelsteine 2,09 pro 100 000. Eine signifikante Zunahme der Operationsraten uber die Jahre war fur bosartige und gutartige Tumoren sowie Speichelsteine zu beobachten. Die Operationsraten waren insgesamt am hochsten bei Patienten >60 Jahre. Es waren regionale Schwankungen der Operationsraten zwischen den Bundeslandern zu erkennen. Diskussion: Erstmalig werden Operationsraten fur Eingriffe an Speicheldrusen berichtet. Insbesondere Eingriffe wegen Speicheldrusenmalignomen sind haufiger als erwartet. Trotz Einfuhrung minimal-invasiver Verfahren erscheinen die Raten an Speicheldrusenresektionen bei Sialadenitis und Sialolithiasis noch sehr hoch.

This is the first population-based analysis of inpatient salivary gland surgery across Germany.Nationwide Diagnosis-Related Groups (DRG) statistics for 2007 to 2011 were analyzed regarding indications for salivary gland surgery based on ICD-10 codes. Age specific surgery rates were calculated for both sexes.Inpatient salivary gland surgical rates in 2007-2011 amounted for incisions (OPS [Classification of Operations and Procedures] code 5-260) 1.43 per 100 000 population, for excisions (5-261) 2.06 per 100 000, for salivary gland resections (5-262) 2.06 per 100 000, and for external incisions (5-270) 0.43 per 100 000. Regarding the mentioned four OPS codes, the surgical rates for benign tumors accounted to 10.08 per 100 000, for sialadenitis (without sialoliths) to 4.00 per 100 000, for malignant tumors to 3.90 per 100 000, and for sialolithiasis to 2.09 per 100 000. The increase of surgical rates from 2007 to 2011 was significant for malignant and benign tumors as well as for salivary stones. The surgical rates were highest for patients60 years.Especially surgery for malignant tumors was more frequent than expected. In spite of the introduction of minimal invasive technique the rates for salivary gland resections in case of sialadenitis or sialolithiasis still seem to be high.

High-performance 20-µm unit-cell two-color detectors using an n-p+-n HgCdTe triple-layer heterojunction (TLHJ) device architecture grown by molecular beam epitaxy (MBE) on (211)-oriented CdZnTe substrates with midwavelength (MW) infrared and long wavelength (LW) infrared spectral bands have been demonstrated. Detectors with nominal MW and LW cut-off wavelengths of 5.5 µm and 10.5 µm, respectively, exhibit 78 K LW performance with >70 % quantum efficiency, reverse bias dark currents below 300 pA, and RA products (zero field of view, 150-mV bias) in excess of 1×103 Ωcm2. Temperature-dependent current-voltage (I–V) detector measurements show diffusion-limited LW dark current performance extending to temperatures below 70 K with good operating bias stability (150 mV ± 50 mV). These results reflect the successful implementation of MBE-grown TLHJ detector designs and the introduction of advanced photolithography techniques with inductively coupled plasma (ICP) etching to achieve high aspect ratio mesa delineation of individual detector elements with benefits to detector performance. These detector improvements complement the development of high operability large format 640×480 and 1280×720 two-color HgCdTe infrared focal plane arrays (FPAs) to support third generation forward looking infrared (FLIR) systems.

For small pixel, infrared (IR) focal plane arrays (FPAs), Raytheon Vision Systems’ architecture for integrated, dual-band detectors uses the sequential mode of the n-p+-n configuration. There is a single indium bump per pixel, leaving the p+ layer floating, and the operating polarity of the bias selects the spectral sensitivity by reverse-biasing the active p-n junction. Photogenerated minority carriers in the absorber layer of the forward-biased inactive photodiode are lost through recombination. This paper is the first report of a new optical crosstalk mechanism that occurs in sequential-mode, dual-band detectors. In the long-wavelength mode under out-of-band, short-wavelength illumination, radiative recombination yields emission near the bandgap energy of the short-wavelength absorber layer, resulting in a spurious short-wavelength response that appears as spectral crosstalk. We present experimental and device modeling results on the spectral crosstalk in molecular-beam-epitaxy-grown HgCdTe arrays with the cutoff wavelength of both bands in the 4–5-µm range.

Raytheon Vision Systems (RVS, Goleta, CA) in collaboration with HRL Laboratories (Malibu, CA) is contributing to the maturation and manufacturing readiness of third-generation, dual-color, HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256×256 30-µm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long wavelength infrared (LWIR) spectral regions. The FPAs configured for MWIR/MWIR, MWIR/LWIR, and LWIR/LWIR detection are used for target identification, signature recognition, and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all dual-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art, single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single-mesa, single-indium bump, and sequential-mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.

The heteroepitaxial growth of HgCdTe on large-area Si substrates is an enabling technology leading to the production of low-cost, large-format infrared focal plane arrays (FPAs). This approach will allow HgCdTe FPA technology to be scaled beyond the limitations of bulk CdZnTe substrates. We have already achieved excellent mid-wavelength infrared (MWIR) and short wavelength infrared (SWIR) detector and FPA results using HgCdTe grown on 4-in. Si substrates using molecular beam epitaxy (MBE), and this work was focused on extending these results into the long wavelength infrared (LWIR) spectral regime. A series of nine p-on-n LWIR HgCdTe double-layer heterojunction (DLHJ) detector structures were grown on 4-in. Si substrates. The HgCdTe composition uniformity was very good over the entire 4-in. wafer with a typical maximum nonuniformity of 2.2% at the very edge of the wafer; run-to-run composition reproducibility, realized with real-time feedback control using spectroscopic ellipsometry, was also very good. Both secondary ion mass spectrometry (SIMS) and Hall-effect measurements showed well-behaved doping and majority carrier properties, respectively. Preliminary detector results were promising for this initial work and good broad-band spectral response was demonstrated; 61% quantum efficiency was measured, which is very good compared to a maximum allowed value of 70% for a non-antireflection-coated Si surface. The R0A products for HgCdTe/Si detectors in the 9.6-µm and 12-µm cutoff range were at least one order of magnitude below typical results for detectors fabricated on bulk CdZnTe substrates. This lower performance was attributed to an elevated dislocation density, which is in the mid-106 cm−2 range. The dislocation density in HgCdTe/Si needs to be reduced to

The flexible nature of molecular-beam epitaxy (MBE) growth is beneficial for HgCdTe infrared-detector design and allows for tailored growths at lower costs and larger focal-plane array (FPA) formats. Control of growth dynamics gives the MBE process a distinct advantage in the production of multicolor devices, although opportunities for device improvement still exist. Growth defects can inhibit pixel performance and reduce the operability in FPAs, so it is important to understand and evaluate their properties and impact on detector performance. The object of this paper is to understand and correlate the effects of macrodefects on two-color detector performance. We observed the location of single-crystal and polycrystalline regions on planar and cross-sectioned surfaces of two-color device structures when void defects were viewed by scanning electron microscopy (SEM). Compositional analysis via energy dispersive x-ray analysis (EDXA) of voids in the cross section showed elevated Te and reduced Hg when compared to defect-free growth areas. The second portion of this study examined the correlation of macrodefects with pixel operability and diode current-voltage (I–V) characteristics in mid-wavelength infrared (MWIR)/MWIR (M/M) and long wavelength infrared (LWIR)/LWIR (L/L) two-color devices. The probability of diode failure when a void is present is 98% for M/M and 100% for L/L. Voids in two-color detectors also impact diodes neighboring their location; the impact is higher for L/L detectors than M/M detectors. All void-containing diodes showed early breakdown in the I–V characteristics in one or both bands. High dislocation densities were observed surrounding voids; the high density spread further from the void for L/L detectors compared to M/M detectors.

The application of spectroscopic ellipsometry (SE) for real-time composition determination during molecular beam epitaxy (MBE) growth of Hg1-xCdxTe alloys with x > 0.5 is reported. Techniques previously developed for SE determination of composition in long-wavelength infrared (LWIR) HgCdTe have been successfully extended to near-infrared HgCdTe avalanche photodiode (APD) device structures with x values in the range of 0.6-0.8. Ellipsometric data collected over a spectral range of 1.7-5 eV were used to measure depth profiles of HgCdTe alloy composition through the use of an optical model of the growth surface. The optical model used a dielectric-function database collected through the growth of a set of HgCdTe calibration samples with x ranging from 0.6 to 0.8. The sensitivity of this SE method of composition determination is estimated to be Δx ∼ 0.0002 at x = 0.6, which is sufficiently low to sense composition changes arising from flux variations of less than 0.1%. Errors in composition determination because of Hg-fiux variations appear to be inconsequential, while substrate-temperature fluctuations have been observed to alter the derived composition at a rate of -0.0004/°C. By comparing the composition inferred from SE and postgrowth 300 K IR transmission measurements on a set of APD device structures, the run-to-run precision of the SE-derived composition (at x = 0.6) is estimated to be ±0.0012, which is equivalent to the precision achieved with the same instrumentation during the growth of mid-wavelength infrared (MWIR) HgCdTe alloys in the same MBE system.

Results are reported on the molecular-beam epitaxial (MBE) growth and electrical performance of HgCdTe midwave-infrared (MWIR) detector structures. These devices are designed for operation in the 140–160 K temperature range with cutoff wavelengths ranging from 3.4–3.8 µm at 140 K. Epitaxial structures, grown at 185°C on (211)B-oriented CdZnTe substrates, consisting of either conventional two-layer P-n configurations or three-layer P-n-N configurations, were designed to examine the impact of device performance on variation of the n-type base layer (absorber) thickness and the inclusion or omission of an underlying wide-bandgap buffer layer. Devices were grown with absorber thicknesses of 3 µm, 5 µm, and 7 µm to examine the tradeoff between the spectral response characteristic and the reverse-bias electrical performance. In addition, 5-µm-thick, wide-bandgap HgCdTe buffer layers, whose CdTe mole fraction was approximately 0.1 larger than the absorber layer, were introduced into several device structures to study the effect of isolating the device absorbing layer from the substrate/growth initiation interface. The MBE-grown epitaxial wafers were processed into passivated, mesa-type, discrete device structures and diode mini arrays, which were tested for temperature-dependent R0A product, quantum efficiency, spectral response, and the I-V characteristic at temperatures close to 140 K. External quantum efficiencies of 75–79% were obtained with lateral optical-collection lengths of 7 µm. Analysis of the temperature dependence of the diode R0A product indicates that the device impedance is limited by the diffusion current at temperatures above 140 K with typical R0A values of 2×106 Ω cm2 for a detector cutoff of 3.8 µm at 140 K. An alloy composition anomaly at the absorbing-layer/buffer-layer interface is believed to limit the observed R0A products to values approximately one order of magnitude below the theoretical limit projected for radiatively limited carrier lifetime. Device electrical performance was observed to be improved through incorporation of a wide-bandgap buffer layer and through reduction of the absorbing layer thickness. An optimum spectral response characteristic was observed for device structures with 5-µm-thick absorbing layers.

We have developed the capability to grow HgCdTe mid-wave infrared radiation double-layer heterojunctions (MWIR DLHJs) on 4″ Si wafers by molecular beam epitaxy (MBE), and fabricate devices from these wafers that are comparable to those produced by mature technologies. Test data show that the detectors, which range in cutoff wavelength over 4–7 μm, are comparable to the trendline performance of liquid phase epitaxy (LPE)-grown material. The spectral characteristics are similar, with a slight decrease in quantum efficiency attributable to the Si substrate. With respect to R0A, the HgCdTe/Si devices are closer to the theoretical radiative-limit than LPE-grown detectors. Known defect densities in the material have been correlated to device performance through a simple model. Slight 1/f noise increases were measured in comparison to the LPE material, but the observed levels are not sufficient to significantly degrade focal plane array (FPA) performance. In addition to discrete detectors, two FPA formats were fabricated. 128×128 FPAs show MWIR sensitivity comparable to mature InSb technology, with pixel operability values in excess of 99%. A 640×480 FPA further demonstrates the high-sensitivity and high-operability capabilities of this material.

HgCdTe p-on-n double layer heterojunctions (DLHJs) for mid-wave infrared (MWIR) detector applications have been grown on 100 mm (4 inch) diameter (211) silicon substrates by molecular beam epitaxy (MBE). The structural quality of these films is excellent, as demonstrated by x-ray rocking curves with full widths at half maximum (FWHMs) of 80–100 arcsec, and etch pit densities from 1 106 to 7 106 cm−2. Morphological defect densities for these layers are generally less than 1000 cm−2. Improving Hg flux coverage of the wafer during growth can reduce void defects near the edges of the wafers. Improved tellurium source designs have resulted in better temporal flux stability and a reduction of the center to edge x-value variation from 9% to only 2%. Photovoltaic MWIR detectors have been fabricated from some of these 100mm wafers, and the devices show performance at 140 K which is comparable to other MWIR detectors grown on bulk CdZnTe substrates by MBE and by liquid phase epitaxy.

Future wideband communications, mm-wave digital synthesis, and digital beam-steering will benefit from digital operation at clock frequencies between 50 and 100 GHz at reasonable power levels. HRL has developed InP-based HBT technology that is capable of supporting these needs. We have demonstrated InP HBTs with cutoff frequencies, ft, over 200 GHz and with f max over 300 GHz as well as fully static dividers operating at 72.8 GHz.

As the number of bands and the complexity of HgCdTe multicolor structures increases, it is desirable to minimize the lattice mismatch at growth interfaces within the device structure in order to reduce or eliminate mismatch dislocations at these interfaces and potential threading dislocations that can degrade device performance. To achieve this we are investigating the use of Hg1−x−yCdxZnyTe quaternary alloys which have an independently tunable lattice constant and bandgap. Lattice matching in Hg1−x−yCdxZnyTe structures can be achieved using small additions of Zn (y

Progress on achieving reproducible growth of high performance, dual-band IR detector structures in HgCdTe grown by molecular beam epitaxy (MBE) is described. The reproducibility achieved in the MBE growth of n-p-n device structures comprising HgCdTe epitaxial layers with different composition and doping characteristics was evaluated from the run-to-run precision in the alloy composition, dopant concentration and dislocation density. For a series of 25 growth runs, the standard deviation of the alloy composition in the n-type absorbing layer was 0.002; the yield for the in situ n- and p-type doping process was > 95%; and the average dislocation density was < 5 x 10 5 cm -2 . In situ optical diagnostics, including spectroscopic ellipsometry and an optical absorption flux monitor were used for the real-time determination of the alloy composition and Cd flux during MBE growth of the two-color device structures. Focal plane arrays with 128 x 128 elements were fabricated for the simultaneous detection of two sub-bands in the MWIR spectrum. Average R o A values exceeding 1 x 10 6 and 2 x 10 5 Ω cm 2 were measured at 77 K for diodes operating at 4.0 and 4.5 μm, respectively, and the quantum efficiency was greater than 70% in each band. These results on MBE growth and device performance demonstrate that HgCdTe MBE technology is poised for the modest-scale production of advanced IR devices.

Transmission electron microscopy (TEM) was used to evaluate the microstructure of molecular beam epitaxy (MBE) grown (211)B oriented HgCdTe films. TEM analysis of in-situ doped p-on-n and n-p-n device structures will be presented. Under fully optimized growth conditions the substrate-epilayer interface is free of threading dislocations and twins, and a high degree of structural integrity is retained throughout the entire device structure. However, under non-optimal growth conditions that employ high Hg/Te flux ratios, twins can be generated in the p-type layer of p-on-n device structure, resulting in roughness and facetting of the film surface. We propose a mechanism for twin formation that is associated with surface facetting. TEM evaluation of voids, threading dislocations and Te-precipitates in HgCdTe films are also discussed.

Yield/density relationships of two spring cultivars of oilseed rape were investigated under five different plant densities. Densities ranged from 20 to 130 plants m−2. Three response variables, number of pods per plant, seed weight per plant and dry matter per plant, were studied using different regression models to examine their relationship with density. Transformations were used to improve the fit of the models. Pods per plant, seed weight and dry matter per plant decreased as plant density increased. Seed weight and dry matter m−2 responded similarly to varying plant density for the two cultivars. For all response variables, the inverse exponential model gave the best fit to the data, indicating the existence of an optimum density, which was about half the official recommended sowing density.

We describe an integrated real-time sensing and control system for monitoring and controlling substrate temperature, layer composition, and effusion cell flux during molecular beam epitaxial growth of HgCdTe epilayers for advanced IR detectors. Substrate temperature is monitored in real-time using absorption-edge spectroscopy, allowing the temperature to be controlled within 1.5°C of the desired setpoint. In situ spectroscopic ellipsometry (SE) is used for monitoring HgCdTe layer composition in real-time. A comprehensive temperature- and composition-dependent dielectric function database has been recorded which allows the accurate and precise determination of Hg1−xCdxTe layer composition over a wide range of x-values, from 0.2 to 0.42. The composition changes inferred from real-time SE measurements obtained during growth of a two-layer structure are in excellent agreement with composition profiles obtained using post-growth secondary ion mass spectroscopy analysis. The accuracy and precision of SE measurements conducted over multiple growth runs are shown to be suitable for robust SE-based composition control. Changes in the Cd flux produced by a CdTe effusion cell are detected using an atomic optical absorption method. This method allows changes in HgCdTe layer composition to be correlated directly with variations in Cd flux. All of the in situ sensors are linked using a custom software framework to provide the foundation for real-time monitoring and control of HgCdTe MBE growth of high performance infrared detector structures over a wide range of compositions, layer thicknesses, and substrate temperatures.

We review the rapid progress that has been made during the past three years in the heteroepitaxial growth of HgCdTe infrared detector device structures on Si substrates by molecular-beam epitaxy. The evolution of this technology has enabled the fabrication of high performance, large-area HgCdTe infrared focal-plane arrays on Si substrates. A key element of this heteroepitaxial approach has been development of high quality CdTe buffer layers deposited on Si(112) substrates. We review the solutions developed by several groups to address the difficulties associated with the CdTe/Si(112) heteroepitaxial system, including control of crystallographic orientation and minimization of defects such as twins and threading dislocations. The material quality of HgCdTe/Si and the performance of HgCdTe detector structures grown on CdTe/Si(112) composite substrates is reviewed. Finally, we discuss some of the challenges related to composition uniformity and defect generation encountered with scaling the MBE growth process for HgCdTe to large-area Si substrates.

Molecular-beam epitaxy (MBE) has been utilized to fabricate HgCdTe heterostructure separate absorption and multiplication avalanche photodiodes (SAM-APD) sensitive to infrared radiation in the 1.1-1.6 μm spectral range, as an alternative technology to existing III-V APD detectors. Device structures were grown on CdZnTe(211)B substrates using CdTe, Te, and Hg sources with in situ In and As doping. The composition of the HgCdTe alloy layers was adjusted to achieve both efficient absorption of IR radiation in the 1.1-1.6 μm spectral range and low excess-noise avalanche multiplication. The Hg 1-x Cd x Te alloy composition in the gain region of the device, = 0.73, was selected to achieve equality between the bandgap energy and spin-orbit splitting to resonantly enhance the impact ionization of holes in the split-off valence band. The appropriate value of this alloy composition was determined from analysis of the 300 K bandgap and spin-orbit splitting energies of a set of calibration layers, using a combination of IR transmission and spectroscopic ellipsometry measurements. MBE-grown APD epitaxial wafers were processed into passivated mesa-type discrete device structures and diode mini-arrays using conventional HgCdTe process technology. Device spectral response, dark current density, and avalanche gain measurements were performed on the processed wafers. Avalanche gains in the range of 30-40 at reverse bias of 85-90 V and array-median dark current density below 2 x 10 -4 A/cm 2 at 40 V reverse bias have been demonstrated.

Molecular beam epitaxy was employed for the growth of HgCdTe-based n-p+-n device structures on (211)B oriented CdZnTe substrates. The device structures were processed as mesa isolated diodes, and operated as back-to-back diodes for the simultaneous detection of two closely spaced sub-bands in the mid-wave infrared spectrum. The devices were characterized by R0A values in excess of 5 × 105 Ω cm2 at 78K, at f/2 fov and quantum efficiencies greater than 70% in each band. Infrared imagery from a focal plane array with 128 × 128 pixels was acquired simultaneously from each band at temperatures between 77 to 180K, with no observable degradation in the image quality with increase in temperature.

Root parasites of the genus Orobanche cause serious losses in many subtropical crops. Direct control options are very limited and crop yield loss can reach 100%. Prediction of potential damage in a crop before sowing or planting would support farmers in their choice of crop. This paper discusses the relationship between the number of Orobanche spp. seeds in the field and yield loss in peas (Pisum sativum L.) and carrots (Daucus carota L.) in Israel. Yield loss due to Orobanche crenata Forsk. in peas was 100% at high infestations, whereas in carrots when O. crenata and O. aegyptiaca were present it stabilized at about 50% for moderate infestations of 200 seeds per kg of soil. Statistical analyses related the yield loss from parasitism in peas and carrots to the numbers of Orobanche seeds remaining in the soil. A rectangular hyperbolic model, previously applied to competition data, fitted the data well. Confidence intervals for per cent yield loss were calculated using the bootstrap method. The practical applications of these models in predicting yield loss are discussed.

Molecular beam epitaxy has been employed to deposit HgCdTe infrared detector structures on Si(112) substrates with performance at 125K that is equivalent to detectors grown on conventional CdZnTe substrates. The detector structures are grown on Si via CdTe(112)B buffer layers, whose structural properties include x-ray rocking curve full width at half maximum of 63 arc-sec and near-surface etch pit density of 3–5 × 105 cm−2 for 9 µm thick CdTe films. HgCdTe p+-on-n device structures were grown by molecular beam epitaxy (MBE) on both bulk CdZnTe and Si with 125K cutoff wavelengths ranging from 3.5 to 5 µm. External quantum efficiencies of 70%, limited only by reflection loss at the uncoated Si-vacuum interface, were achieved for detectors on Si. The current-voltage (I-V) characteristics of MBE-grown detectors on CdZnTe and Si were found to be equivalent, with reverse breakdown voltages well in excess of 700 mV. The temperature dependences of the I-V characteristics of MBE-grown diodes on CdZnTe and Si were found to be essentially identical and in agreement with a diffusion-limited current model for temperatures down to 110K. The performance of MBE-grown diodes on Si is also equivalent to that of typical liquid phase epitaxy-grown devices on CdZnTe with R0A products in the 106–107 Θ-cm2 range for 3.6 µm cutoff at 125K and R0A products in the 104–105 Θ-cm2 range for 4.7 µm cutoff at 125K.

In situ doped HgCdTe two-color detectors with the n-p-n geometry were grown by molecular beam epitaxy, for the simultaneous detection of two closely spaced bands in the mid-wave infrared spectrum. The average near-surface etch pit densities in these layers were 5 x10 6 cm -2 , which is a factor of 10 higher than that observed for the lattice-matched growth of Hg 1-x Cd x Te (x =0.22) layer on Cd 0.96 Zn 0.04 Te substrates. The 0.04% lattice mismatch between the Hg 1-x Cd x Te (x = 0.35) epilayer and the Cd 0.9 Zn 0.04 Te substrate produces plastic deformation of the epilayer which results in an increased dislocation densities in the epilayer. The alloy composition across the device structure along the growth direction was determined by secondary ion mass spectrometric analysis, and deviated by less than 1% from the target. The device structures were processed as diodes with the mesa architecture and tested. The spectral response of the detectors at 77 K was characterized by sharp turn off at 3.7 and 4.4 μm. R 0 A values in excess of 1 x 10 6 Ω cm 2 and quantum efficiencies greater than 75% were measured for diodes in each band.

High-performance in situ doped two-color detectors with the n-p-n architecture for the sequential detection of mid: and long-wave infrared radiation were grown by molecular beam epitaxy. These detector structures were twin-free, and exhibited narrow rocking curves ( 45 arcsec) as determined by X-ray measurements. The near surface etch pit densities in these device structures were typically (2-3) x 10 6 cm -2 . The structures were processed as mesas and their electrical properties measured. The spectral response of the mid-wave and long-wave diodes in the integrated detector were characterized by sharp turn-on and turn-off in both bands. Average R o A values of 100 Ω cm 2 at 10.5 μm and 5.5 x 10 5 Ω cm 2 at 5.5 μm were measured at 77 K. These results are comparable to those of the best unispectral detectors and represents a significant milestone for MBE-grown HgCdTe two-color devices

A packaged D-type flip-flop (DFF) decision circuit for optical OC-768 systems and testing equipment is reported. The circuit uses 1 /spl mu/m InP SHBT technology featuring f/sub T//f/sub max/=150 GHz and has been operated up to 45 Gb/s with a clock phase margin about 180/spl deg/. Measured output eye diagrams from packaged devices exhibit 9/8 ps rise/fall with only 3ps peak-peak jitter. A single-ended AC-coupled clock input makes the application of this circuit very convenient. The IC dissipates 440 mW from a -4V supply voltage.

Optical limiting has been investigated for higher fullerenes and compared with C60. The transmission through an aperture placed after solutions of C76, C78, and C84 in tetrahydronaphthalene was measured using Q-switched laser pulses with a wavelength of 532 nm and a pulse width of 8 ns FWHM. Unlike C60, the transmission for these higher fullerene solutions decreased linearly with increasing optical pulse energy. We attribute the linearized optical limiting response to self-defocusing of the optical beam and the absence of excited-state absorption. The ground state absorption spectra for the higher fullerenes suggest their use for optical limiting in the near infrared, and the C84-tetrahydronaphthalene solution was found to be an optical limiter at 1.064 μm.

High-quality, single-crystal epitaxial films of CdTe(112)B and HgCdTe(112)B have been grown directly on Si(112) substrates without the need for GaAs interfacial layers. The CdTe and HgCdTe films have been characterized with optical microscopy, x-ray diffraction, wet chemical defect etching, and secondary ion mass spectrometry. HgCdTe/Si infrared detectors have also been fabricated and tested. The CdTe(112)B films are highly specular, twin-free, and have x-ray rocking curves as narrow as 72 arc-sec and near-surface etch pit density (EPD) of 2 × 106 cm−2 for 8 µm thick films. HgCdTe(112)B films deposited on Si substrates have x-ray rocking curve FWHM as low as 76 arc-sec and EPD of 3-22 × 106 cm−2. These MBE-grown epitaxial structures have been used to fabricate the first high-performance HgCdTe IR detectors grown directly on Si without use of an intermediate GaAs buffer layer. HgCdTe/Si infrared detectors have been fabricated with 40% quantum efficiency and R0A = 1.64 × 104 Ωm2 (0 FOV) for devices with 7.8 µm cutoff wavelength at 78Kto demonstrate the capability of MBE for growth of large-area HgCdTe arrays on Si.

A robust process has been developed for the reproducible growth of in-situ doped Hg1−xCdxTe:As alloys by molecular beam epitaxy. Net hole concentrations in excess of 5 x 1017 cm−3, with peak mobilities >200 cm2/Vs were measured in Hg0.74Cd0.26Te:As films. The p-type layers were twin-free and consistently exhibit narrow x-ray rocking curves (

II–VI materials have numerous optoelectronic applications such as HgCdTe for IR imaging and ZnSe for full color flat panel, optical recording and under-water communications. p-Type doping in II–VI materials was one of the major technological hurdles. However, significant progress has been made in II–VI molecular-beam epitaxy (MBE) technology over the last two years. In the narrow bandgap HgCdTe arena, device quality materials have been grown with alloy compositions required for short to long-wavelength applications. Specifically, high performance IR imaging arrays (64 × 64) have recently been fabricated using MBE-grown double layer p-on-n structure. In addition, dual-band detectors and injection IR diode lasers have been demonstrated recently also with the HgCdTe MBE technology. In the wide bandgap arena, many MBE groups worldwide have been extensively pursuing research in ZnSe-related compounds. It is anticipated that the improvement in II–VI MBE technology will continue to accelerate in the next few years for manufacturing of optoelectronic devices.

A high frequency millimeter-wave voltage-controlled oscillator (VCO) has been designed, manufactured and tested in InP single heterojunction bipolar transistor technology. The fully integrated fundamental differential VCO features high operating frequency up to 80 GHz with low phase noise about -118 dBc/Hz at 1-MHz offset and 5% tuning range. The VCO consumes only 95-mW power at a power supply of -5 V, while providing -2 dBm single-ended output power and 1 dBm for differential output power. The die size is 0.28 mm/sup 2/.

A broadband limiting amplifier is designed, manufactured, and measured using 1 ?m InP SHBT technology with fT/fmax= 160GHz/160GHz. The lumped-element differential amplifier achieves a DC-43GHz bandwidth with a 30dB differential gain, which gives the highest gain-bandwidth product (1.36 THz) reported so far in any technology. In addition to S-parameter measurements, a 47Gb/s operational speed in time domain is obtained with small time jitter added. The differential output amplitude is 1V with 8/8ps rise/fall times. The die size is only 0.7mm2. Total power dissipation is 0.5W with a ?4V power supply.

Raytheon Vision Systems (RVS) is developing two-color and large format single color FPAs fabricated from molecular beam epitaxy (MBE) grown HgCdTe triple layer heterojunction (TLHJ) wafers on CdZnTe substrates and double layer heterojunction (DLHJ) wafers on Si substrates, respectively. MBE material growth development has resulted in scaling TLHJ growth on CdZnTe substrates from 10cm2 to 50cm2, long-wavelength infrared (LWIR) DLHJ growth on 4-inch Si substrates and the first demonstration of mid-wavelength infrared (MWIR) DLHJ growth on 6-inch Si substrates with low defect density ( 70% quantum efficiency, diffusion limited reverse bias dark currents below 300pA and RA products (zero field-of-view, +150mV bias) in excess of 1×103 Ωcm2. Two-color 20μm unit-cell 1280×720 MWIR/LWIR FPAs with pixel response operability approaching 99% have been produced and high quality simultaneous imaging of the spectral bands has been achieved by mating the FPA to a readout integrated circuit (ROIC) with Time Division Multiplexed Integration (TDMI). Large format mega pixel 20μm unit-cell 2048×2048 and 25μm unit-cell 2560×512 FPAs have been demonstrated using DLHJ HgCdTe growth on Si substrates in the short wavelength infrared (SWIR) and MWIR spectral range. Recent imaging of 30μm unit-cell 256×256 LWIR FPAs with 10.0-10.7μm 78K cut-off wavelength and pixel response operability as high as 99.7% show the potential for extending HgCdTe/Si technology to LWIR wavelengths.

Raytheon Vision Systems (RVS) is developing two-color, large-format infrared FPAs to support the US Army’s Third Generation FLIR systems**. RVS has produced 640 x 480 two-color FPAs with a 20 P m pixel pitch. Work is also underway to demonstrate a 1280 x 720 two-color FPA in 2005. The FPA architecture has been designed to achieve nearly simultaneous temporal detection of the spectral bands while being producible for pixel dimensions as small as 20 microns. Raytheon’s approach employs a readout integrated circuit (ROIC) with Time Division Multiplexed Integration (TDMI). This ROIC is coupled to bias-selectable two-color detector array with a single contact per pixel. The two-color detector arrays are fabricated from MBE-grown HgCdTe triple layer heterojunction (TLHJ) wafers. The single indium bump design is producible for 20 P m unit cells and exploits mature fabrication processes that are in production at RVS for Second Generation FPAs. This combination allows for the high temporal and spatial color registration while providing a low-cost, highly producible and robust manufacturing process. High-quality MWIR/LWIR (M/L) 640 x 480 TDMI FPAs with have been produced and imaged from multiple fabrication lots. These FPAs have LWIR cutoffs ranging to 11 P m at 78K. These 20 P m pixel FPAs have demonstrated excellent sensitivity and pixel operabilities exceeding 99%. NETDs less than 25 mK at f/5 have been demonstrated for both bands operating simultaneously. Keywords: HgCdTe, infrared detectors, focal plane arrays, multi-spectral, two-color, 3

A packaged 43-Gb/s clock and data recovery circuit with 1:2 demux in a 1/spl mu/m InP SHBT technology is reported. A half-rate phase/frequency detector incorporating a four-phase LC-ring oscillator is implemented in the phase and frequency locked loop thus eliminating an external reference clock as a frequency acquisition aid. Measured pull-in and hold-in ranges are 0.9 GHz and 1.1 GHz, respectively, with a peak-to-peak clock jitter of 4.5 ps at 43-Gb/s input data rate.

This chapter focuses on the current status of HgCdTe molecular-beam epitaxy (MBE) growth technology as practiced in laboratory. The chapter addresses the following topics: a summary of the ‘hardware’ aspects of MBE growth technology, including the role of process sensors, a discussion of the key parameters of the epitaxial growth process and associated thin-film material properties, and a discussion of current state-of-the-art results in device application areas that have been particularly well-served by the evolution of HgCdTe MBE technology. Significant progress has been achieved in HgCdTe MBE growth technology that has enabled the synthesis of complicated multilayer infrared (IR) detector device structures. The development and integration of in situ sensors for monitoring and control of the sensitive HgCdTe MBE growth process, has significantly advanced the capabilities and consistency of the technology, culminating in demonstrations of excellent device performance in a wide variety of IR device architectures such as multispectral detectors, near-IR avalanche photodiodes (APD), high-performance medium wavelength infrared (MWIR) detectors, and megapixel arrays on Silicon (Si) substrates. Cryopumps have found widespread use in MBE systems designed for the growth of HgCdTe alloys. The epitaxial growth of device-quality HgCdTe by MBE is extremely sensitive to fundamental growth parameters such as source fluxes and substrate temperature. MBE growth of HgCdTe generally utilizes Hg, CdTe, and Te as source materials. HgCdTe alloys, because of their unique energy band structure, can be designed to provide low-excess-noise carrier multiplication. MBE growth technology, besides allowing for the integration of sensors that can be used to precisely control the process, also offers the added benefit of excellent lateral uniformity in HgCdTe epitaxial material quality.

This report presents the results of research on compliant substrate behavior in III-V semiconductors grown by molecular beam epitaxy (MBE) on thin (50-80A) InGaAs layers on GaAs, and in II-VI semiconductors (HgCdTe, CdTe, ZnTe) grown on thin Si(211) layers on Si(100). A comprehensive experimental study was conducted utilizing spectroscopic ellipsometry, transmission electron microscopy, and atomic force microscopy at various stages in the fabrication and processing of the compliant layers and during MBE growth on those layers. Contrary to earlier reports by other investigators, we obtained no evidence for defect reduction or solid phase atomic rearrangement due to substrate compliancy in either of the III-V or II-V systems studied here. We conclude that the early reports of compliancy may have been erroneous interpretation of limited experimental data. Indeed, a theoretical consideration of stress relief mechanics in semiconductor thin films suggests that many of the proposed compliancy mechanisms are not feasible. Although no evidence of substrate compliancy was obtained, we were nevertheless successful in growing high quality II-VI layers by MBE on thin Si(211) layers bonded to Si(100) substrates. This has important implications for monolithic integration of HgCdTe infrared focal plane arrays with readout circuitry fabricated in Si(100) substrates.

Dose-response models are intensively used in herbicide bioassays. Despite recent advancements in the development of new herbicides, statistical analyses are commonly based on asymptotic approximations that are sometimes poor. This paper presents the use of recent results in higher order asymptotics for likelihood-based inference in nonlinear regression. The methods presented provide accurate approximation for the distribution of test statistics and for prediction limits. Analyses of the fit and measures of detection limits of the bioassays are considered, and the potential of the methods is illustrated by examples with real data.

A case of osteomalacia due to vitamin D deficiency in a 25 year old female immigrant from Pakistan is described. Symptoms consisted of low back and hip pain, associated with proximal muscle weakness and waddling gait. Laboratory evaluation revealed low 25 hydroxy vitamin D, secondary hyperparathyroidism and high serum levels of alkaline phosphatases.

A case of pregnancy associated osteoporosis in a 26 year-old woman's first pregnancy is described. Four months after delivery of a normal boy, the patient presented with back pain and fractures of the thoracic spine (Th 6, 7 and 9). The patient was treated with calcium and vitamin D. After three years the bone density was within normal range and had increased by 19.1% in the hip and 15.8% in the spine, respectively. Bone biopsy and extensive biochemical examinations including collagen analysis could not find any explanation for the observed fractures other than pregnancy.

One-year outcomes of older adults referred for community aging and mental health services through the Gatekeeper Model were examined in this study. Outcomes included level of social, physical, psychological, and economic isolation, physical health problems, service need, and service utilization. Findings indicate that individuals referred by gatekeepers were more likely to live alone and to be socially isolated but less likely to have physical health problems. They were also less likely to have a physician at referral, but at 1 year this difference was not found. Cognitive problems had a significant impact on the lives of clients referred by gatekeepers at referral but not after one year. At referral, those referred by gatekeepers had greater service needs, but after 1 year they did not use more services than those referred by other sources. Implications of these findings are discussed. The findings from this study indicate that the adoption of the Gatekeepers model does not result in high service utilization. The Gatekeeper model is inexpensive to implement and can benefit communities through increased collaboration among service providers.

Sociodemographics, clinical characteristics, and life stressors of community-dwelling suicidal risk and nonsuicidal risk elders referred to a community aging and mental health provider were compared in this study. Information was collected through case manager surveys and agency records on 683 older adults referred to the Elder Services Program of Spokane Mental Health in 1994 and the first 6 months of 1995. This sample included 109 individuals who were clinically judged to be at suicide risk by case managers at the time of initial assessment. Comparisons between suicidal risk and nonsuicidal risk elders indicated that suicidal elders were younger, more likely to be separated or divorced, and more likely to report a previous history of suicidal behavior. Results of a logistic regression analysis indicated that living alone, depression or anxiety disorder, and higher levels of emotional disturbance predicted suicide risk status. In addition, medical problems, family conflict, and relationship loss predicted suicide risk status in this particular sample. Individuals at suicide risk were also more likely to have a family physician than others. Implications of findings for identification and treatment of suicidal elders are discussed.

This article describes the client characteristics and services needs of community-dwelling older adults found through a unique case-finding model developed at the Spokane Mental health Center. The model trains the employees of community businesses and corporations who work with the public to serve as community gatekeepers by identifying and referring community-dwelling older adults who may be in need of aging and/or mental health services. These community case-finders perform a gatekeeping function for older adults that is similar to that performed by schools and the workplace for younger persons. Information was collected on 777 individuals aged 60 and older referred over an 18-month period (January 1, 1994, to June 30, 1995) to the Spokane Mental Health Clinical Case Management Program in Spokane, Washington, which provides aging and mental health services to older adults residing in the county. Findings indicate that 40% of clients referred were found by community-based gatekeepers. Clients referred by gatekeepers were more frequently socially isolated, economically disadvantaged, and less likely to have a physician. Gatekeeper clients were also more likely to be women and to be younger than others referred to the agency. Gatekeeper clients were receiving fewer services at referral and were identified as needing more services at intake. Gatekeepers find a distinct population of community-dwelling older adults who are not found by more traditional referral sources. The need to integrate this model within a comprehensive clinical case management system is discussed.