| Summary: | 碩士 === 國立東華大學 === 材料科學與工程學系 === 98 === Due to the excellent microwave performances and current handing capability, heterojunction bipolar transistors (HBTs) have attracted considerable attention in wireless communication and power amplifier applications. In this thesis, the InGaP/GaAsSb/GaAs and InGaP/GaAs/GaAs HBTs structures fabricated by metal organic chemical vapor deposition. Form the DC characteristics and gummel plot, we can see that InGaP/GaAsSb junction has smaller conduction band barrier. And, its smaller offset voltage reduces the power consumption in circuit applications.
The oxidation of base surface arises the surface states, causes the formation of Fermi level pinning effect and makes recombination current rise. Therefore, this study uses X-ray photoelectron spectroscopy and electrical characteristics demonstrate whether device characteristics improved or not.
Experimental results demonstrate that passivation of compound semiconductors removes the native oxide layer followed by the formation of a thin protection layer on the surface to prevent their oxidation.
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