(Invited) InGaSb MOSFET Channel on Metamorphic Buffer: Materials, Interfaces and Process Options

Abstract

High quality bulk GaSb and InGaSb quantum wells grown on GaAs substrates were MBE grown using a AlGaSb(As) metamorphic buffer layers to reduce dislocation density down to 107cm-2. Strained In0.36Ga0.64Sb quantum wells with a biaxial compressive strain of 1.8% showed the highest mobility of 1020 cm2/Vs and a low sheet resistance of 3.9 kΩ/sq. at hole sheet at hole density of 1.9x1012 cm-2. Buried channel design with an AlGaSb top barrier improved hole mobility by only 30% compared to surface QW channels. Improving the interface trap density down to 1012 cm-2eV-1 was realized using an amorphous Si layer (in-situ gate oxide) or an InAs layer (ex-situ gate) as a gate passivation. p++-GaSb epitaxial contact layers were developed and showed the leakage current of ~0.1 mA/cm2 not affected by growth defects. Critical elements of "gate-last" InGaSb MOSFET fabrication process were developed utilizing an InAs etch stop layer to avoid high temperature processing of the gate stack.