The Study on Effects of AlGaAs/GaAs Heterojunction Bipolar Transistor with Ammonium Sulfide Treatment

• Main Authors: Lih-Min Chen, 陳力民
• Other Authors: Yan-Kuin Su
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/33155300101416119966

碩士 === 中原大學 === 電子工程研究所 === 90 === Abstract Because of the high-current gain, operation speed, and low switch on voltage of the AlGaAs/GaAs Heterojunction Bipolar Transistors (HBTs), especially to applicate in microwave, high power, and low bias systems, but many applications will require HBTs to operate in high power density environments, the device performances were decaded because of the heat which created by itself and extrinsic environments that the heat can not dissipated to air from substrate due to the low thermal conductivity of the GaAs materials; except to the effect of thermal, the weakness of the AlGaAs/GaAs HBTs is the high surface recombination velocity (about 106 cm/s) that before the oxide layer deposited. In the thesis, an AlGaAs/GaAs HBT was fabricated; the Emitter, Collector and Base characteristic resistances could be 10-6 W-cm2, and the current gain b can to 100. To observe the surface state with optic-microscopy, SEM, and AFM, the surface state has became better after ammonium sulfide treated; analysis the surface components with XPS and the diffusion effect was proved by AES; the thermal effect was discussed, the current and current gain were decaded because the sulfide layer reduce the heat dissipated to air. The DC performance was improved by ammonium sulfide treated because of the surface passivation effect, however the RF performances were reduced, because of the sulfide effect is a diffusion effect and increased the base resistance.