Exploring SiSn as channel material for LSTP device applications

We present a novel semiconducting alloy, Silicon-tin (SiSn), as a channel material for LSTP device applications. The diffusion of Sn into silicon has been explored to demonstrate, for the first time, a MOSFET using SiSn as channel material. The semiconducting alloy SiSn offers interesting possibilities in the realm of silicon bandgap tuning and strain engineering. Previous works have shown that Sn diffuses into silicon wafer [1], and that the SiSn alloy is semiconducting [2]. Further, recent studies have shown better MOSFET performance with GeSn as channel material, as compared to Ge [3, 4]. To complement these activities, we have explored diffusion of tin (Sn) into industry's most widely used substrate - silicon (100). The diffusion process of Sn into the silicon lattice is low cost, scalable and manufacturable. We have studied SiSn as a channel material using theoretical analysis, as well as, by MOSFET fabrication. We observe better switching performance and an order-of-magnitude reduction in Ioff of the SiSn pMOSFETs, while maintaining a similar Ion, compared to the Si devices. We also note that the Ion/Ioff ratio for pMOSFETs is improved with incorporation of Sn into the channel.