We present a comparative study of the effects of a Si capping layer on SiGe channel pMOSFETs used for radio-frequency (RF) applications. In Si-capped devices, the drive current increases because Si/SiGe heterojunction layers form a SiGe quantum well, which reduces carrier scattering. Conversely, SiGe samples without a Si capping layer suffer severe interface degradation, due to Ge diffusing into the gate dielectric. Devices using a Si capping layer have enhanced RF performance and reduced low-frequency noise, which is a key factor affecting phase noise. There is an increase in the RF figures of merit. These benefits indicate that a Si capping layer should be used in SiGe channel pMOSFETs.
Bibliographical noteFunding Information:
Manuscript received June 10, 2010; revised July 18, 2010; accepted July 18, 2010. Date of publication August 23, 2010; date of current version September 24, 2010. This work was supported in part by the Ministry of Education, Science and Technology through the National Research Foundation of Korea under the World Class University Program R31-2008-000-10100-0, by the BK21 program, by the “System IC 2010” project, and by the National Center for Nanomaterials Technology, Korea. The review of this letter was arranged by Editor J. Cai.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering