Title :
Electron space-charge effects on high-frequency performance of AlGaAs/GaAs HBTs under high-current-density operation
Author :
Morizuka, Kouhei ; Katoh, Riichi ; Tsuda, Kunio ; Asaka, Masayuki ; Iizuka, Norio ; Obara, Masao
Author_Institution :
Toshiba Res. & Dev. Centre, Kawasaki, Japan
Abstract :
The high-frequency characteristics of AlGaAs/GaAs heterojunction bipolar transistors (HBTs) under high-current-density biasing condition are investigated in conjunction with the electron space charge in the collector depletion layer. A significant increase in cutoff frequency f/sub t/ and maximum oscillation frequency f/sub max/ at the early stage of the base push-out was observed in HBTs with a lightly doped n-type collector structure, and is attributed to the collector depletion layer widening and the enhancement of the velocity overshoot effect caused by the increasing electron density.<>
Keywords :
III-V semiconductors; aluminium compounds; gallium arsenide; heterojunction bipolar transistors; space charge; AlGaAs-GaAs; HBTs; III-V semiconductors; biasing condition; collector depletion layer; collector depletion layer widening; cutoff frequency; electron space charge; heterojunction bipolar transistors; high-current-density operation; high-frequency performance; lightly doped n-type collector structure; maximum oscillation frequency; velocity overshoot effect; Bipolar transistors; Current density; Current measurement; Cutoff frequency; Electrons; Frequency measurement; Gallium arsenide; Heterojunction bipolar transistors; Kirk field collapse effect; Space charge;
Journal_Title :
Electron Device Letters, IEEE
