EXPERIMENTAL CHARACTERIZATION AND MODELING ANALYSIS ON NPN AlGaN/GaN HBT WITH HIGH IDEALITY FACTOR IN BOTH COLLECTOR AND BASE CURRENT

Abstract

Characterization and modeling analysis on both ideality factor of the collector current (η C ) and the base current (η B ) have higher than the excepted values of 1.0 and 2.0, respectively, for npn Al GaN/GaN heterojunction bipolar transistors (HBTs) have been reported. We employ the rapid thermal process annealing (RTP-annealing) to modify the base parasitical Schottky diode (called A-HBTs) after the as-deposited Ni/Au bilayers on the base layer for electrode with no annealing (called N-HBTs) to compare with each other. For a HBT operated in Gummel-plot configuration, experimental and modeling results indicate that the base parasitical Schottky diode (BPSD) causes the base current (I B ) and collector current (I C ) with high ideality factor and raise the base-emitter voltage (V BE ) to higher operation point, and therefore lead to more power consumption. Furthermore, the extended Ebers–Moll equivalent-circuit model together with the extracted device parameters provided simulated results that were in a good agreement with experimental ones.