Quantum well field-effect transistors with composite spacer structures, apparatus made therewith, and methods of using same

摘要

A quantum well (QW) layer is provided in a semiconductive device. The QW layer is covered with a composite spacer above QW layer. The composite spacer includes an InP spacer first layer and an InAlAs spacer second layer above and on the InP spacer first layer. The semiconductive device includes InGaAs bottom and top barrier layers respectively below and above the QW layer. The semiconductive device also includes a high-k gate dielectric layer that sits on the InP spacer first layer in a gate recess. A process of forming the QW layer includes using an off-cut semiconductive substrate.