The Study On The Preparation Of Silicon Based Ge_1-xSn_x Alloy Nanoclusters And Their Photodetection Properties

Photoelectric detectors are of great value in industrial and military field,also in environmental monitoring,biological science and medical care.However,the indirect bandgap property of silicon-based materials leads to the low optical efficiency and the narrow bandwidth.This in turn leads to a relatively large signal-to-noise ratio and also a low light response rate of room temperature silicon-based light detectors,which seriously restricts the development of silicon-based light detectors.Compared with traditional silicon-based materials,Ge Sn alloy materials can greatly improve the optical efficiency and bandwidth of silicon-based materials because of their adjustable band gap.However,the extremely low solid solution of Sn in Ge makes it difficult to prepare a high-component,high-crystallinity Ge Sn alloy.Coating Ge Sn nanocrystals with SiO₂ can improve the solid solution of Sn in Ge and prepare high-component Ge Sn nanocrystals,which combines the joint regulation of the energy band by the effect of components and nanosize and is expected to achieve more efficient optoelectronic devices.Therefore,in this thesis,the nanoclusters of silicon-based Ge_1-xSn_x alloy are prepared by magnetron sputtering method to study their photoelectric detection performance.The main research contents and results of this thesis are as follows:（1）Ge_1-xSn_x-SiO₂ composite film was prepared by RF co-sputtering method,Ge sheet and Sn sheet were attached to SiO₂ targets,and Ge Sn-SiO₂ films were formed by sputtering Ge,Sn and SiO₂ at the same time by using radio frequency（Radio Frequency,RF）sputtering method,and annealed at different temperatures to form SiO₂-coated Ge_1-xSn_x nano-crystals(Ge_1-xSn_x nano-crystals,Ge_1-xSn_x NCs).Then,the components of Sn in Ge_1-xSn_x NCs were controlled by changing the number of Sn pieces,and the effect of annealing temperature on the sample components was studied.Finally,the microstructure of the sample was studied with tools such as scanning electron microscopy and atomic force microscopy.Highly crystalline,highly composed Ge_1-xSn_x NCs with annealing Ge_1-xSn_x-SiO₂ composite film at 50 W sputtering power,sputtering temperature of 300°C,and annealing at 450°C were obtained,and the Sn component was about 18.3%.（2）A photodetector with ITO/Ge_1-xSn_x-SiO₂/N⁺-SiMIS（Metal-Insulator-Semiconductor,MIS）structure was constructed,and the light response and occurrence mechanism of the device under different sputtering power and annealing temperature were studied.It was concluded that the devices obtained had better performance at a sputtering power of 50 W,a sputtering temperature of 300°C,and annealing of 450°C.It operates stably at 1 V bias and has short response times of 21.2/16.8 ms,switching ratios of 8.50×10⁴,responses of 4.3×10^-3（A/W）,and detection rates of 2.49×10⁹ Jones under 532 nm laser irradiation.