Interface-controlled Si/SiGe-heterostructure growth and its device application

Si/SiGe heterostructures were grown by molecular-beam epitaxy. With atomic- hydrogen irradiation during the growth of the heterostructure, characterist ics of modulation-doped field-effect transistors (MODFETs) were improved. A Hall effect measurement and a device simulation revealed that carrier dens ity capable of being confined in the Si channel is limited in the MODFETs. Surface-Channel metal-oxide-semiconductor field-effect transistors (MOSFETs ) with strained-Si channel on various buffer layers were fabricated. Effect ive electron mobility in strained-Si MOSFETs with a Sice compositionally gr aded buffer layer was 60% higher than that of an unstrained-Si MOSFET. The enhancement of mobility varied with the types of the buffer layers. This va riation may be attributed to the amplitude of surface roughness of the stra ined-Si layer. (C) 2000 American Vacuum Society.