Electron Mobility Enhancement in GeSn n-Channel MOSFETs by Tensile Strain

摘要

A record high electron mobility of 698 cm(2)/N.s in a tensile-strained Ge0.96Sn0.04 nMOSFET is demonstrated in this letter. High-quality GeSn films were epitaxially grown by low-temperature chemical vapor deposition. Different strain conditions in the active GeSn layers were achieved by Ge or GeSn relaxed buffers. A mesa FET structure was used to effectively reduce the OFF leakage by a recessed p junction in Ge. The I-ON/I-OFF ratio in the mesa GeSn FETs is boosted by a factor of 100 compared to conventional planar devices. As the GeSn film becomes more tensile strained, the channel mobility is enhanced, which could be attributed to a higher carrier population in the Gamma valley.