Fabrication of a sii-ægeæ channel metal-oxide-semiconductor field-effect transistor (Mosfet) containing high ge fraction layer by low-pressure chemical vapor deposition

A method for growing the high-quality strained epitaxial heterostructure of Si/Sii-^Ge^/Si by low-pressure chemical vapor deposition (CVD) and the fabrication of Sii-aGe^-channel metal-oxide-semiconductor field-effect transistors (MOSFET’s) with a high Ge fraction layer have been investigated. It is found that lowering of the deposition temperature of the Sii-xGeæ and Si capping layers is necessary with increasing Ge fraction in order to prevent island growth of the layers. With the use of the optimized fabrication process, Si/Sii-xGeæ/Si heterostructures with flat surfaces and interfaces were realized, and a high-performance Sio.sGeo.s-channel MOSFET has been achieved with a large mobility enhancement of about 70% at 300 K and over 150% at 77 K compared with that of a MOSFET without a Sii-sGe^ channel.