Si-Ge-Si SEMICONDUCTOR STRUCTURE HAVING DOUBLE COMPOSITIONALLY-GRADED HETERO-STRUCTURES AND METHOD FOR FORMING THE SAME

Abstract

A Si—Ge—Si semiconductor structure having double compositionally-graded hetero-structures is provided, comprising: a substrate; a buffer layer or an insulation layer formed on the substrate; a strained SiGe layer formed on the buffer layer or the insulation layer, wherein a Ge content in a central portion of the strained SiGe layer is higher than the Ge content in an upper surface or in a lower surface of the strained SiGe layer, and the Ge content presents a compositionally-graded distribution from the central portion to the upper surface and to the lower surface respectively. According to the present disclosure, a compositionally-graded hetero-structure replaces an abrupt hetero-structure so as to form a triangular hole carrier potential well, so that most of hole carriers may be distributed in the strained SiGe layer with high Ge content and a reduction of the carrier mobility caused by interface scattering may be avoided, thus further improving a performance of a device.

Dependencies are inferred from the claim text.