Fabrication of depletion- and enhancement-mode GaInP/GaAs /spl delta/-HEMT's

Abstract

A new HEMT structure was proposed to fabricate both types .f device. Additional n-GaAs cap layer was employed to control the device operation mode. Accordingly, both depletion- and enhancement- mode HEMT's were simultaneously fabricated on the same chip by selectivelv removing the cap layer. For a 1x100 pm2 device, the pinch-c$f voltage for the depletion mode device is -1.8 K The maximum applied gate voltage for the enhancement mode one is +I.8 K The measured output current and transconductance are 260 (200) mA/mm, 175 (150) mS/mm. The measured f t und f ma are 6.3 (6) and 13 (12) GHz for depletion- and enhancement-mode devices, respectively.