Investigate On Silicon Quantum Dot Film And Its Photodetector

Among semiconductor quantum dots,silicon quantum dots（Si-QDs）are excellent luminescent material due to its unique optoelectronic properties,and silicon is non-toxic,green and rich in material resources,these advantages make Si-QDs a popular material for research.With the development and progress of nanoscience,people are interested in the preparation technology,performance optimization and application of Si-QDs.Si-QDs play an important role in many fields such as photovoltaics,solar cells,biomedicine,and photocatalysis.Today,the huge application potential of Si-QDs still attracts the attention of researchers.In recent years,in addition to the high performance of Si-QDs,low-cost and environmentally friendly preparation methods have also become the focus of attention.In this paper,firstly,the carbon-silicon composite films were prepared by co-sputtering with direct current（DC）magnetron sputtering and radio frequency（RF）magnetron sputtering,and the relevant parameters in the preparation process were optimized.Secondly,the effects of different annealing temperatures on the formation of Si-QDs on the surface of the carbon-silicon composite films were studied.The characterization of samples structure and optical properties were carried out by Raman spectroscopy（Raman）,atomic force microscope（AFM）,Leica microscope,X-ray photoelectron spectrometer（XPS）,transmission electron microscope（TEM）and UV-Vis absorption spectrometer.Finally,prototype device based on Si-QDs film was prepared,and the prepared device was characterized and tested with the Keithley 2400test system,revealing its huge application prospects in the field of high-performance photodetectors.The main research content and conclusions of the paper are as follows:1.The carbon-silicon composite films were prepared by DC magnetron sputtering and RF magnetron sputtering co-sputtering n-Si and carbon target.The preparation process of the carbon-silicon composite film was explored,and the films parameter were optimized through a series of characterizations.The thin film prepared by this method is amorphous,and then the samples were treated by different annealing temperature.Comparing the structural characterization results before and after annealing,it is found that the formation of Si-QDs can be observed in the sample after annealing at 400℃and 600℃for 1 h and the Si-QDs will disappear when the annealing temperature is increased.The conversion mechanism of the film from amorphous state to precipitated QDs as the annealing temperature changes was systematically studied.Besides,its optical properties were also investigated.2.The photovoltaic prototype devices based on Si-QDs film photodetectors were prepared,and the prepared devices were tested accordingly.Those results show that Si-QDs film/n-Si photovoltaic device under illumination of the light with power density of 1.13 m Wcm^-2at a wavelength of 940 nm,and applied by bias voltage of 5 V,the monochromatic responsivity（R）reached up to 7.43 AW^-1,and the peak detectivity reached up to 1.25×10¹²cm Hz^1/2W^-1(1 cm Hz^1/2W^-1is equal to 1 Jones).The transient response of the device lighting by 940 nm was also studied to prove its stability.These studies based on Si-QDs thin film devices indicate that Si-QDs thin film have great potential in the development of high-performance photodetectors.