Title :
Improving collector-current uniformity in emitter-graded AlGaAs/GaAs heterojunction bipolar transistors
Author :
Takano, C. ; Taira, K. ; Kawai, H.
Author_Institution :
Sony Res. Center, Yokohama, Japan
fDate :
3/1/1988 12:00:00 AM
Abstract :
To investigate the effect of a graded layer on collector-current uniformity, two types of HBTs were fabricated by metalorganic chemical vapor deposition (MOCVD). One type had a bandgap graded layer at the emitter-based interface to eliminate the conduction-band spike. The other type was a conventional HBT (heterojunction bipolar transistor) with an abrupt heterojunction fluctuated due to the fluctuation of the barrier energy from the emitter to the base. The bandgap-graded layer drastically suppressed the fluctuation of the collector current. the standard deviation of the threshold voltage was improved from 3.03 to 0.42 V by adopting bandgap grading at the emitter-based interface.<>
Keywords :
III-V semiconductors; aluminium compounds; bipolar transistors; chemical vapour deposition; gallium arsenide; 0.42 mV; AlGaAs-GaAs; HBTs; bandgap graded layer; barrier energy; collector-current uniformity; conduction-band spike; emitter-based interface; emitter-graded AlGaAs/GaAs heterojunction bipolar transistors; fluctuation; graded layer; metalorganic chemical vapor deposition; standard deviation; Bipolar transistors; Fluctuations; Gallium arsenide; Gold; Heterojunction bipolar transistors; High speed integrated circuits; MOCVD; Ohmic contacts; Photonic band gap; Zinc;
Journal_Title :
Electron Device Letters, IEEE
