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Pearton S. J. Abernathy C. R. Ren F. Lothian J. R. Kopf R. F. 《Plasma Chemistry and Plasma Processing》1994,14(4):505-522
Dry etching of common masking materials used in GaAs device technology, was examined down to temperatures of –30°C. The etch rates of SiNx, SiO2, and W in SF6/Ar are reduced below 0°C, but the anisotropy of the etching is improved at low temperature. Microwave enhancement of the SF6/Ar discharges produces increases in etch rates of several times at 25°C, but much lower increases at –30°C substrate temperature. The underlying GaAs surface shows increased S and F coverage after low-temperature etching, but these species are readily removerd either by anex-situ wet chemical cleaning step or an in-situ H2 plasma exposure. Photoresist etching is less sensitive to temperature, and anisotropic profiles are produced between –30 and +60°C in pure O2 discharges. 相似文献
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Kingston Kang William Lothian Jessica Sears Brian D. Sutton 《Numerical Algorithms》2014,66(3):479-493
When an orthogonal matrix is partitioned into a two-by-two block structure, its four blocks can be simultaneously bidiagonalized. This observation underlies numerically stable algorithms for the CS decomposition and the existence of CMV matrices for orthogonal polynomial recurrences. We discover a new matrix decomposition for simultaneous multidiagonalization, which reduces the blocks to any desired bandwidth. Its existence is proved, and a backward stable algorithm is developed. The resulting matrix with banded blocks is parameterized by a product of Givens rotations, guaranteeing orthogonality even on a finite-precision computer. The algorithm relies heavily on Level 3 BLAS routines and supports parallel computation. 相似文献
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C. R. Abernathy F. Ren S. J. Pearton T. R. Fullowan R. K. Montgomery P. W. Wisk J. R. Lothian P. R. Smith 《Journal of Crystal Growth》1992,120(1-4):234-239
In this paper, we will discuss how the unique growth chemistry of MOMBE can be used to produce high speed GaAs/AlGaAs heterojunction bipolar transistors (HBTs). The ability to grow heavily doped, well-confined layers with carbon doping from trimethylgallium (TMG) is a significant advantage for this device. However, in addition to high p-type doping, high n-type doping is also required. While elemental Sn can be used to achieve doping levels up to 1.5×1019 cm-3, severe segregation limits its use to surface contact layers. With tetraethyltin (TESn), however, segregation does not occur and Sn doping can be used throughout the device. Using these sources along with triethylgallium (TEG), trimethylamine alane (TMAA), and AsH3, we have fabricated Npn devices with 2 μm×10 μm emitter stripes which show gains of ≥ 20 with either ƒt = 55 GHz and ƒmax = 70 GHz or ƒt = 70 GHz and ƒmax = 50 GHz, depending upon the structure. These are among the best RF values reported for carbon doped HBTs grown by any method, and are the first reported for an all-gas source MOMBE process. In addition, we have fabricated a 70 transistor decision circuit whose performance at 10 Gb/s equals or exceeds that of similar circuits made from other device technologies and growth methods. These are the first integrated circuits reported from MOMBE grown material. 相似文献
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