Impact of Pocket Doped Mg2Si/Si Heterojunction Ge Gated TFET for Low Optical Power Detection at 1550 nm

In this article, Germanium photogated Tunnel Field effect transistor with Magnesium Silicide (Mg2Si)/Silicon (Si) heterojunction and its advancement with heavily n+ doped Si pocket at the source-channel junction has been studied using LUMINOUS module of SILVACO ATLAS-2D TCAD tool at 1550 nm wavelength. Here germanium photoabsorber layer over the complete channel has been incorporated in between gate and the oxide layer that separates the photoabsorber material (Germanium) and conduction region (Mg2Si/Si device) in the proposed phototransistor. Here an n+ silicon pocket has been studied in between Mg2Si source and silicon channel with the advantage of reduced voltage requirements for detecting infrared radiations. The phototransistor performance has been optimized for different pocket lengths and it has been observed that the pocket of 10 nm length is the best sensitive case with the sensitivity of 2.9 × 1010, responsivity of 2.5 × 105 A/W and detectivity of 4.94 × 1017 Jones at optical power of 10−3 µW/µm2 and 0.35 V gate bias requirement.