Research On GeSn PIN Light-emitting Device

The future of information technology development is to achieve the integration of microelectronics technology and photonics technology.more than 90% of the world's electronic devices and circuits are based on silicon,the urgent need for the development of technology is to achieve Si-based photoelectric integration.The bandgap of Ge_1-xSn_x alloy can be continuously adjusted from 0 to 0.67 e V.Moveover,Ge_1-xSn_x alloy is an ideal material platform for Si-based optoelectronic integrated circuits?OEIC?due to its high electrons and hole mobility.So Ge_1-xSn_x LED will play a pivotal role in the future IC industry as a high efficiency solid light source in the new generation of OEIC.In this paper,the band structures of Ge_1-xSn_x alloy were studied using Material Studio.Compared with the bulk germanium material,Ge_1-xSn_x alloy exhibits a significant bandgap shrinkage phenomenon,which means that Ge_1-xSn_x LED has a higher radiation recombination rate and luminous efficiency.When the Sn components reach about 10%,the Ge_1-xSn_x alloy is converted from an indirect bandgap material to a direct bandgap material.Furthermore,Ge_1-xSn_x alloy can be compatible with the traditional Si-based CMOS process.therefore,Ge_1-xSn_x alloy has a bright prospect in the field of OEIC,and meets the requirements of future monolithic and low power.Based on the research of Ge_1-xSn_x alloy and infrared LED in optoelectronic integrated system,an infrared Ge_1-xSn_x PIN LED with double heterojunction structure is designed in this paper.Its photoelectric properties were studied by TCAD simulation software.The results showed that the Ge_1-xSn_x LED exhibits good photoelectric properties,and has an obvious electrochromic response.Primarily,the critical parameters,such as the doping concentration of P / N region,the thickness of intrinsic layer and Sn components have important influence on the performance.To obtain good IV output characteristics,high enough output power and large enough power spectral density,the P / N region of the LED device requires a heavy doping to meet the needs of the actual device applications.In a certain range,the thickness of the intrinsic layer is positively correlated with the IV output characteristic,the output power and the spectral power density.That is to say,increased thickness can achieve better characteristics.However,when the thickness exceeds the range,these properties are negatively correlated.Therefore,the optimization of device needs to select an appropriate thickness of intrinsic layer.In general,the device with large Sn components shows better IV output characteristics,higher output power and greater spectral power density,especially when the Sn components reach about 10%,where the Ge_1-xSn_x alloy is converted from an indirect bandgap material to a direct bandgap material,which greatly increases the photoelectric conversion efficiency of the device.Compared with the vertical emission LED,the edge emission LED exhibits a better electrical characteristics and a little worse optical characteristics,so the structure of the device needs to be moderately selected in the actual application.