Title :
Base transit time in abrupt GaN/InGaN/GaN HBT´s
Author :
Chiu, Shean-Yih ; Anwar, A.F.M. ; Wu, Shangli
Author_Institution :
Dept. of Electr. & Syst. Eng., Connecticut Univ., Storrs, CT, USA
fDate :
4/1/2000 12:00:00 AM
Abstract :
Base transit time in an abrupt GaN/InGaN/GaN HBT is reported. Temperature and doping concentration dependence of low field mobility is obtained from an ensemble Monte Carlo simulation. Base transit time, τb, decreases with increasing temperature. The low temperature τb is dominated by the diffusion constant or, in other words, transport within the neutral base region. However, at elevated temperatures base transit time is dependent more upon the base-collector junction velocity or, in other words, by the transport across the heterointerface. τb increases with In-mole fraction showing a stronger dependence at lower temperatures. Unity gain current cut-off frequency, fT, is a strong function of temperature and base doping concentration. An fT of 20 GHz is obtained for a 0.05 μm HBT
Keywords :
III-V semiconductors; Monte Carlo methods; carrier lifetime; carrier mobility; gallium compounds; heterojunction bipolar transistors; indium compounds; minority carriers; semiconductor device models; wide band gap semiconductors; GaN-InGaN-GaN; abrupt GaN/InGaN/GaN HBT; bandgap narrowing; base doping concentration; base transit time; base-collector junction velocity; carrier degeneracy; diffusion constant; doping concentration dependence; ensemble Monte Carlo simulation; heterointerface transport; linear interpolation; low field mobility; neutral base region transport; temperature dependence; unity gain current cut-off frequency; Cutoff frequency; Gallium nitride; Heterojunction bipolar transistors; Optical devices; Photonic band gap; Semiconductor device doping; Temperature dependence; Thermal factors; Tunneling; Wide band gap semiconductors;
Journal_Title :
Electron Devices, IEEE Transactions on
