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用硫离子直接注入掺铬半绝缘衬底作成沟道区,制成了砷化镓微波场效应晶体管,这样就避免了生长外延层。这一离子注入法已用于制作0.25微米厚、厚度及载流子浓度均匀的n型层,对不同的样品载流子迁移率在2410～3620厘米2/伏·秒范围。由于均匀性好,用此注入层制作的场效应晶体管同一个片子上各个管芯的跨导和夹断电压重复性好,其偏差不超过±10％。通常,掺铬的砷化镓满足于制作场效应晶体管,然而为了获得最高的迁移率希望铬的补偿最小。表征微波特性的S参数测量推算出f_(max)=20千兆赫,然而因阻抗失配和管壳参量的影响,传输增益大约在7千兆赫截止。
Sulfur ions are directly implanted into a doped chromium-based semi-insulating substrate to form a channel region to form a gallium arsenide microwave field-effect transistor, thereby avoiding the growth of an epitaxial layer. This ion implantation method has been used to make n-type layers with a thickness of 0.25 microns, a uniform thickness and carrier concentration. The carrier mobility for different samples is in the range of 2410 to 3620 cm 2 / V · sec. Due to the good uniformity, the transconductance and pinch-off voltage repeatability of each die on the same chip of the same field-effect transistor manufactured by using the injection layer is good, and the deviation is no more than ± 10%. In general, chromium-doped gallium arsenide is sufficient to fabricate field-effect transistors, however, it is desirable that chromium be minimized for maximum mobility. The S-parameter measurement characterizing the microwave properties deduces f max (max) = 20 gigahertz, whereas the transmission gain is around 7 gigahertz due to impedance mismatch and shell and shell parameters.