An on-ledge Schottky potentiometer for the diagnosis of HBT emitter passivation

Author

Pingxi Ma ; Zampardi, P. ; Liyang Zhang ; Chang, M.F.

Author_Institution

Dept. of Electr. Eng., California Univ., Los Angeles, CA, USA

fYear

1999

fDate

17-20 Oct. 1999

Firstpage

55

Lastpage

58

Abstract

A Schottky diode, which contacts the emitter passivation ledge directly, is used as a potentiometer to monitor the effectiveness of the emitter/base junction passivation in AlGaAs/GaAs heterojunction bipolar transistors (HBTs). The function and mechanism of this on-ledge potentiometer are carefully examined and analyzed. With this on-ledge Schottky diode, the emitter ledge potential (V/sub Ledge/) can be measured directly as a function of the base-emitter bias voltage (VBE) By relating V/sub Ledge/ to V/sub BE/, We are able to quantify the extent of the ledge depletion down to a few angstroms (<10 /spl Aring/) in precision. The outstanding detectivity of the on-ledge potentiometer makes itself a very powerful tool in the diagnosis of HBT problems in both device operation and long-term reliability. These problems are not detectable or distinguishable with prior monitoring techniques.

Keywords

III-V semiconductors; aluminium compounds; gallium arsenide; heterojunction bipolar transistors; passivation; potentiometers; semiconductor device measurement; semiconductor device reliability; semiconductor device testing; AlGaAs-GaAs; HBT emitter passivation; III-V semiconductors; Schottky diode; base-emitter bias voltage; detectivity; device operation; long-term reliability; on-ledge Schottky potentiometer; Contacts; Gallium arsenide; Heterojunction bipolar transistors; Monitoring; Passivation; Potentiometers; Resistors; Schottky diodes; Temperature sensors; Voltage;

fLanguage

English

Publisher

ieee

Conference_Titel

GaAs IC Symposium, 1999. 21st Annual

Conference_Location

Monterey, CA, USA

ISSN

1064-7775

Print_ISBN

0-7803-5585-7

Type

conf

DOI

10.1109/GAAS.1999.803726

Filename

803726