The performance of surface channel MOSFET devices is dependent on the Si/SiO2 interface roughness. This paper examines the performance demonstrated by strained Si/SiGe heterojunction n-channel MOSFET devices (HNMOSFETs) fabricated on ultra-low pressure CVD (ULPCVD) material compared with unstrained Si control devices. The surface channel HNMOSFETs were found to exhibit performance enhancements in terms of transconductance of approximately 135% compared with their Si counterparts. In addition, the electrical characteristics of the HNMOSFETs displayed increased uniformity and improvements in the peak transconductance in excess of 75% compared with equivalent devices fabricated on strained Si/SiGe GS-MBE material. Atomic force microscopy and transmission electron microscopy showed that the favourable characteristics of the ULPCVD strained Si/SiGe devices are due to reduced cross-hatch severity of the ULPCVD material, which is shown to decrease nanoscale roughness at the Si/SiO2 interface. (C) 2003 Published by Elsevier Science Ltd.