A pilot production Zone-melting Recrystallization system was designed and built with a capability to handle 25 wafer batches of 4“, 5“and 6“wafers. The design addresses several production requirements including high throughput, batch processing and automation. Measurements on product wafers indicate that material quality was not sacrificed to achieve production throughput levels. Exceptional structural quality and good electrical properties have been obtained on SOI wafers produced within this system. Specifically, defect densities as low as 5 X 104 /cm2 a level an order of magnitude lower than previously reported, have been achieved while the minority carrier lifetime of up to 30 microseconds, intrinsic dopant level < 2 X 1015 /cm3 and junction leakage below 1 X 1016 amperes/cm2 are either as good as or better than previously reported values. We believe that defect free ZMR material will become a reality.

GaAs single junction solar cells were fabricated on epitaxial liftoff (ELO) 4:″ GaAs wafers. 1 cm 2 single junction GaAs solar cells have been fabricated with a yield ≫80% across full 4″ ELO wafers. Photoluminescence studies of ELO GaAs wafers showed no evidence of residual strain in the layers as indicated by single peak at 870 nm at 300 K. Transmission electron microscopy studies of ELO solar cells indicated no evidence of threading dislocations, voids or delaminating at the semiconductor-metal interface. Quantum efficiency measurements on ELO GaAs single junction solar cells indicated improved performance near the band edge in the ELO samples compared with conventional, non-ELO GaAs cells. GaAs ELO solar cells exhibited efficiencies in excess of 21% with V oc = 1.007 V and FF≫85%.

We have built plastic displays for SmartCards by integrating high‐quality, crystalline silicon NanoBlock IC drivers using a Fluidic Self Assembly (FSA®) process. With this low‐cost, high‐volume manufacturing approach, flexible peripheral driver strips are now being readied for application to commercial liquid crystal and OLED display products.

AlGaAs emitter heterojunction bipolar transistors (HBTs) are demonstrated to have excellent dc and RF properties comparable to InGaP/GaAs HBTs by increasing the Al composition. Al/sub 0.35/Ga/sub 0.65/As/GaAs HBTs exhibit very high dc current gain at all bias levels, exceeding 140 at 25 A/cm/sup 2/ and reaching a maximum of 210 at 26 kA/cm/sup 2/ (L=1.4 /spl mu/m/spl times/3 /spl mu/m, R/sub sb/=330 /spl Omega///spl square/). The temperature dependence of the peak dc current gain is also significantly improved by increasing the AlGaAs mole fraction of the emitter. Device analysis suggests that a larger emitter energy gap contributes to the improved device performance by both lowering space charge recombination and increasing the barrier to reverse hole injection.

AlGaAs emitter heterojunction bipolar transistors (HBT's) are demonstrated to have excellent dc and RF prop- erties comparable to InGaP/GaAs HBT's by increasing the Al composition. Al Ga As/GaAs HBT's exhibit very high dc current gain at all bias levels, exceeding 140 at 25 A/cm and reaching a maximum of 210 at 26 kA/cm ( m m, ). The temperature dependence of the peak dc current gain is also significantly improved by increasing the AlGaAs mole fraction of the emitter. Device analysis suggests that a larger emitter energy-gap contributes to the improved device performance by both lowering space charge recombination and increasing the barrier to reverse hole injection.

We demonstrate that GaAs-based HBTs with very low base currents at both low and high injection levels can be achieved using either Al 0.35Ga0.65As or InGaP in the emitter with the proper optimization of structure and growth. We observe an order of magnitude reduction in space charge recombination current as the Al composition, and hence the energy-gap, of the emitter increases from 25% (1.77 eV) to 35% (1.89 eV). AlGaAs/GaAs HBTs with approximately 35% Al have the same energy-gap as InGaP and exhibit comparable space charge recombination in large area devices (L = 75 x 75 μm). Moreover, this reduction in the space charge recombination in Al0.35Ga0.65As/GaAs HBTs can be achieved while maintaining a low turn-on voltage and high DC current gain over a wide range of current densities. Small area devices (L = 1.4 x 3 μm) fabricated with an Al 0.35Ga0.65As emitter and a base sheet resistance of 330 Ω/† exhibit very high DC current gain at all bias levels, with a DC current gain exceeding 140 @ 25 A/cm 2 and a peak DC current gain of 210 @ 26 kA/cm. The temperature dependence of the peak DC current gain is significantly improved over a similar structure with a 25% AlGaAs emitter. The RF performance of the 35% AlGaAs structure is also comparable to the 25% structure, with an ft of 34 GHz and an f max of 55 GHz.

Very high dc current gain in InGaP/GaAs heterojunction bipolar transistors (HBTs) was demonstrated. The dc current gain/base sheet resistance ratio (41319 cm(-3) @700 Angstrom) in large area devices (L = 5625 mum(2)) was 0.6. A comparison of low and high gain HBT devices clearly showed an enhancement in the effective minority carrier lifetime of the base layer. Small area devices (L = 4 mum(2)) exhibited a current gain of 132 at 60 kA/cm(2). The base current at low current densities was low indicating low space charge recombination which is one of the key characteristics of InGaP/GaAs HBTs. Selected devices were tested for extended reliability under high junction temperatures of up to 363degreesC and at a high current density (60 kA/cm(2)). The MTTF (mean time to failure) was extrapolated to 5 x 105 hours at 150degreesC junction temperature (Ea = 0.68 eV). These results are attributed to the superior material parameters of InGaP in the HBT (high valence band offset (DeltaEv >0.30 eV), low surface recombination, high energy gap, and long minority carrier lifetime).

Neutral base recombination is a limiting factor controlling the maximum gain of AlGaAs/GaAs HBT's with base sheet resistances between 100 and 350 /spl Omega///spl square/. In this work, we investigate five series of AlGaAs/GaAs HBT growths in which the base thickness was varied between 500 and 1600 /spl Aring/ and the base doping level between 2.9/spl times/ and 4.7/spl times/10/sup 19/ cm/sup -3/. The dc current gain of large area devices (L=75 /spl mu/m/spl times/75 /spl mu/m) varies by as much as a factor of two at high injection levels for a fixed base sheet resistance, depending on the growth optimization. One of these series (Series TA) has the highest current gains ever reported in this base sheet resistance range, with dc current gains over 225 (@ 200 A/cm/sup 2/) at a base sheet resistance of 330 /spl Omega///spl square/. A high dc current gain of 220 (@ 10 kA/cm/sup 2/) was also confirmed in small area devices (L=8 /spl mu/m/spl times/8 /spl mu/m). High-frequency tests on a separate set of wafers grown under the same conditions indicate these high current gains can be achieved without compromising the RF characteristics: Both high and normal gain devices exhibit an f/sub t//spl sim/68 GHz and f/sub max//spl sim/100 GHz. By fitting the base current as a sum of two components, one due to recombination in the neutral base and the other in the space charge region, we conclude that an improvement in the minority carrier lifetime is responsible for the observed increase in dc current gain. Moreover, we observe a thickness-dependent variation in the effective minority carrier lifetime as the gains increase, along with a nonlinear dependence of current gain on base doping. Both phenomena are discussed in terms of an increase in Auger and radiative recombination relative to Hall-Shockley-Read recombination in optimized samples.

The insertion of advanced microwave devices into high-volume applications is critically dependent upon a robust and reproducible epitaxial growth technology accompanied with a reproducible process technology. The precise control of the material and device parameters is essential to maintain a high-yield process, which leads to a low-cost product. Although AlGaAs/GaAs heterojunction bipolar transistors have been widely demonstrated in many company research laboratories and universities, the transition from a laboratory environment to high-volume production requires a thorough understanding of the metalorganic chemical vapor deposition growth process and its correlation with device performance. In this work, high-performance AlGaAs/GaAs heterojunction bipolar transistors grown by MOCVD with excellent control in the device parameter tolerances have been demonstrated in very high volumes.

InGaP/GaAs based Heterojunction Bipolar Transistors are becoming the leading device for a wide variety of applications including power amplifiers, high speed A/D converters, low noise receivers, and low phase noise oscillators. This device can be designed to operate from L-band to millimeter waves. The excellent reliability of InGaP HBTs at high current densities and high device junction temperatures offers increased performance margins for high frequency and high power applications. At J(c) = 25 kA/cm(2) and T-j = 264 C, no device failures were reported out to 10,000 hours. Reliability data extracted at a higher junction temperature of up to 360 C and at a current density of 60 kA/cm(2) showed an extrapolated MTTF of 5 x 10(5) hours at T-j = 150 C.

Excellent long term reliability InGaP/GaAs heterojunction bipolar transistors (HBT) grown by metalorganic chemical vapor deposition (MOCVD) are demonstrated. There were no device failures (T = 10000 h) in a sample lot of ten devices (L = 6.4 mu m x 20 mu m) under moderate current densities and high-temperature testing (J(c) = 25 kA/cm(2), V-ce = 2.0 V, Junction Temp = 261 degrees C). The de current gain for large area devices (L = 75 mu m x 75 mu m) at 1 kA/cm(2) at a base sheet resistance of 240 ohms/sq (4 x 10(19) cm(-3) @ 700 Angstrom) was over 100. The de current gain before reliability testing (L = 6.4 mu m x 10 mu m) at 0.8 kA/cm(2) was 62. The de current gain (0.8 kA/cm(2)) decreased to 57 after 10000 h of reliability testing. The devices showed an f(T) = 61 GHz and f(max) = 103 GHz. The reliability results are the highest ever achieved for InGaF/GaAs HBT and these results indicate the great potential of InGaP/GaAs HBT for numerous low- and high-frequency microwave circuit applications. The reliability improvements are probably due to the initial low base current at low current densities which result from the low surface recombination of InGaP and the high valence band discontinuity between InGaP and GaAs.

During the past several years we have been developing technology for the creation of 3D microelectronics. Our 3D circuits are fabricated using standard bulk CMOS processing and are then transferred from one wafer to another. The transfer process allows alignment of the layers. The resulting structure consists of lower substrate and associated circuitry, with one or more thin-film circuit layers st...

Npn abrupt AlGaAs/GaAs heterojunction bipolar transistors with thin base widths (W-B) down to 200 Angstrom have been fabricated for the first time, and their collector and base current-voltage characteristics have been studied. The experimental results show that the surface recombination base current and the base bulk recombination current are both significantly lower in 200 Angstrom base HBTs than in comparable devices with 500 Angstrom base width. For the thin base HBTS, the base bulk recombination current density is proportional to similar to W-B and the surface recombination current density is proportional to similar to W-B(2). The experiment also showed that the collector current across a thin p(+) GaAs base is limited, as expected, by the thermal velocity of the electrons rather than by conventional diffusive transport.

1995 International Conference on Solid State Devices and Materials,Active Matrix Liquid Crystal Displays(AMLCD's) and Active Matrix Electroluminescent (AMEL) Displays Using Silicon-On-Insulator(SOI) Technology