Title :
Aluminum graded-base AlGaAs/GaAs PNp HBT with 37 GHz cut-off frequency
Author :
Kameyama, A. ; Massengale, A. ; Dai, C. ; Harris, J.S., Jr.
Author_Institution :
Solid State Lab., Stanford Univ., CA, USA
Abstract :
A PNp AlGaAs/GaAs heterojunction bipolar transistor (HBT) with Al-alloy graded base structure is described. In order to reduce the base transit time (/spl tau/b) and thus to obtain high performance pnp-type AlGaAs/GaAs HBTs, Al-alloy grading is adopted to form a high quasi-electric field in the base. The effectiveness of Al-alloy grading in the base is demonstrated by the RF performance of the fabricated device which shows a cut off frequency (f/sub t/) of 37 GHz and a maximum oscillation frequency (f/sub max/) of 30 GHz. Further analysis of f/sub t/ associated with collector current densities indicates the intrinsic time of the device, which is the sum of the base transit time (/spl tau//sub b/) and the collector depletion region transition time (/spl tau//sub SC/), is as low as 2.0 ps.<>
Keywords :
III-V semiconductors; aluminium compounds; current density; equivalent circuits; gallium arsenide; heterojunction bipolar transistors; microwave bipolar transistors; semiconductor device models; 30 GHz; 37 GHz; Al-alloy graded base structure; AlGaAs-GaAs; RF performance; base transit time reduction; collector current densities; collector depletion region transition time; cutoff frequency; heterojunction bipolar transistor; high quasi-electric field; maximum oscillation frequency; microwave device; pnp-type HBT; Aluminum; Current density; Cutoff frequency; Doping; Gallium arsenide; Heterojunction bipolar transistors; Kirk field collapse effect; Molecular beam epitaxial growth; Radio frequency; Research and development;
Conference_Titel :
Electron Devices Meeting, 1994. IEDM '94. Technical Digest., International
Conference_Location :
San Francisco, CA, USA
Print_ISBN :
0-7803-2111-1
DOI :
10.1109/IEDM.1994.383435
