Enhanced Sensitivity in IR GeSn Thin-Film Based Phototransistors by Using a Gaussian Doping Profile

In this work, a new infrared (IR) phototransistor (PT) structure employing thin-film-transistor (TFT) building block and GeSn sensitive layer with Gaussian doping profile (GDP) is proposed. Accurate numerical models based on Silvaco software are developed. The impact of an engineered doping on the performance of the analyzed TFT PT based on GeSn sensitive layer (SL) is investigated. It is found that the the use GD profile can allow achieving enhanced photoresponse characteristics, while maintaining reduced noise effects. This is attributed to enhanced carrier transfer due to the generation of an electric field across the GeSn SL, facilitating carrier injection to the TFT platform. The GD profile is optimized and the associated device performances are compared with recent works, where higher current ratio, improved detectivity and superior responsivity are achieved. This innovative approach using GD profile, significantly enhances the device performances, offering a promising avenue for the development of alternative PTs for optical wireless communication systems (OWCS).