Noise performance of Si/Si1-xGex FETs

Noise characteristics are evaluated for SiGe/Si based n-channel MODFETs and p-channel MOSFETs. The analysis is based on a self-consistent solution of Schrodinger and Poisson´s equations. The model predicts a superior minimum noise figure for an n-channel MODFET at 77 K. P-channel MOSFETs behave similar to n-channel devices operating at 300 K. Minimum noise figure decreases with increasing quantum well (QW) width for both n- and p-channel devices. However, the p-channel devices are less sensitive to QW width variation. Minimum noise temperature behaves similarly. As observed, a range of doped epilayer thickness exists where minimum noise figure is a minimum for both n- and p-channel FETs.