Nonlinear parasitics in MODFETs and MODFET I-V characteristics

Author

Roblin, Patrick ; Rice, L. ; Bibyk, Steven B. ; Morkoç, Hadis

Author_Institution

Dept. of Electr. Eng., Ohio State Univ., Columbus, OH, USA

Volume

35

Issue

8

fYear

1988

fDate

8/1/1988 12:00:00 AM

Firstpage

1207

Lastpage

1214

Abstract

A large-signal analysis of the source and drain resistance of MODFETs is reported. Velocity saturation in the two-dimensional electron gas (2DEG) and hypothetical rectifying effects in the n⁺-AlGaAs-i-GaAs interface are accounted for. Rectifying effects are found to be either absent or negligible. Current limitations in the 2DEG lead to the observed compression of the transconductance at large gate voltages, and an improved fit of the MODFET I-V characteristics is demonstrated using an approximate analytic formulation of the current-limited parasitic resistance. The high-frequency dependence of the source and drain resistance is also reported. A decrease of the source impedance for frequencies increasing from 1-30 GHz is predicted and can reach 30%, depending on the device structure. Such a frequency decrease of the parasitics is consistent with the reported increase of the effective transconductance of MODFETs at microwave frequencies. The reported frequency and current-limited parasitic models rely on parameters that can either be measured or calculated and are therefore appropriate for CAD applications

Keywords

III-V semiconductors; aluminium compounds; gallium arsenide; high electron mobility transistors; semiconductor device models; solid-state microwave devices; 1 to 30 GHz; AlGaAs-GaAs; MODFET I-V characteristics; MODFETs; analytic formulation; current-limited parasitic models; current-limited parasitic resistance; drain resistance; high-frequency dependence; hypothetical rectifying effects; large gate voltages; large-signal analysis; microwave frequencies; models; nonlinear parasitics; semiconductors; source impedance; source resistance; transconductance; two-dimensional electron gas; Contact resistance; Electrons; Frequency; HEMTs; MODFETs; Ohmic contacts; Propagation delay; Temperature; Transconductance; Voltage;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/16.2539

Filename

2539