Ge outdiffusion effect on flicker noise in strained-Si nMOSFETs

Abstract—The flicker noise characteristics of strained-Si nMOS-FETs are significantly dependent on the gate oxide formation. At high temperature (900 C) thermal oxidation, the Si intersti-tials at the Si/oxide interface were injected into the underneath Si–SiGe heterojunction, and enhanced the Ge outdiffusion into the Si/oxide interface. The Ge atoms at Si/oxide interface act as trap centers, and the strained-Si nMOSFET with thermal gate oxide yields a much larger flicker noise than the control Si device. The Ge outdiffusion is suppressed for the device with the low temperature (700 C) tetraethylorthosilicate gate oxide. The capacitance–voltage measurements of the strained-Si devices with thermal oxide also show that the Si/oxide interface trap density increases and the Si–SiGe heterojunction is smeared out due to the Ge outdiffusion. Index Terms—Flicker noise, Ge outdiffusion, strained-Si, MOSFET