A 1-10 GHz interface engineered SiN/sub x//InP/InGaAs HIGFET technology

The evolution of an unique interface control layer (ICL) SiN/sub x//lnP/InGaAs Heterojunction Insulated Gate (HIG)FET technology is described from its inception. An In-S monolayer ICL, formed by a novel photoelectrochemical process, is used to reduce and control trap states at the SiN/sub x//InP interface. Buried channel insulated gate ICL HIGFETs fabricated using this approach operate over a large gate voltage range (V/sub gs/=/spl plusmn/8 V) with very low gate leakage (10 nA@V/sub gs/=/spl plusmn/5 V) and I/sub ds/(sat) of 250 mA/mm. Undoped channel ICL HIGFETs exhibit transconductance (g/sub m/) of 40 mS/mm that is limited by conduction through the buffer layer. A 3 to 4 fold improvement in g/sub m/ (140-150 mS/mm) is achieved by using a doped InGaAs channel and eliminating parallel conduction paths through the device. The doped channel HIGFETs show f/sub t/ of 5-6 GHz (Lg=3 /spl mu/m) and f/sub max/ of 10-12 GHz with a power gain of 14.2 dB at 3 GHz. The ICL HIGFET technology has been used to construct simple circuits such as buffer amplifiers with a gain of 7-10 dB at 3 GHz and recently, high frequency sample and hold ICL HIGFET circuits that operate at frequencies of 2 GHz.