Abstract :
Results from a detailed simulation study are presented to help evaluate the pros and cons of a wide-gap hydrogenated amorphous silicon emitter (a-Si:H) introduced to improve the injection efficiency at the emitter-base junction of a GaAs bipolar transistor. For a set of devices withstanding the same maximum emitter-collector voltage, it is shown that the current gain, besides a net dependence on the defect state concentration at the emitter-base interface, is also strongly influenced by the base thickness and doping. The base thickness, however, has a weak impact on the cut-off frequency, which in turn shows a clear dependence on the emitter electron mobility. The study predicts that the current thin film silicon technology would allow the fabrication of a transistor performing a DC current gain close to 3000 and a cut-off frequency in excess of 15 GHz. Owing to the simplicity of fabrication, such a device could represent an effective way of adding a bipolar stage to a GaAs MESFET IC without resorting to AlGaAs/GaAs heterostructures
Keywords :
III-V semiconductors <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; amorphous semiconductors <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; electron mobility <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; elemental semiconductors <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; gallium arsenide <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; heterojunction bipolar transistors <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; hydrogen <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; semiconductor device models <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; silicon <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; switching <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; wide band gap semiconductors <a-Si:H/GaAs heterojunction bipolar transistors, improved DC and AC characts., design>; 15 GHz; AC characteristics; DC characteristics; Si:H-GaAs; a-Si:H/GaAs HBTs; base doping; base thickness; current gain; cut-off frequency; defect state concentration; emitter base junction; emitter electron mobility; heterojunction bipolar transistors; injection efficiency; maximum emitter-collector voltage; n-p-n HBTs; simulation study; wide-gap hydrogenated amorphous Si emitter;
