Preparation Of Two-Dimensional Materials Of Group ?-?A And Research On Related Devices

Two-dimensional layered semiconductor materials have unique electronic structures and quantum size effects,and have attracted widespread attention in the fields of energy,microelectronics,optics,and photoelectronic devices.Among them,the two-dimensional layered materials of group ?-?A have also become hot research topics in recent years due to their low cost,rich elements,and environmental friendliness.At the same time,the two-dimensional materials of group ?-?A also have rich layered crystal structures and novel physical properties,and show great application prospects in optical and photoelectronic devices.However,compared with the current mainstream transition metal chalcogenides,the research work of two-dimensional materials in the ?-?A group in all directions are in the initial stage,and the research is relatively poor.This article would focus on the preparation of single crystal germanium sulfide and germanium selenide two-dimensional materials,layer-thinning,electrical testing and optical characterization.Firstly,the research work on graphene,transition metal chalcogenide,and black phosphorus are summarized.Secondly,the research status of two-dimensional materials of group ?-?A in recent years is summarized,and the crystal structures and physical properties of several two-dimensional materials of group ?-?A are introduced,as well as the progress of these materials in field-effect-transistors,photodetections and a variety of device fabrication prospects.Finally,the content,purpose and significance of the research work in this paper are briefly summarized.Next,it introduces several common equipment and instruments used in this paper and their principles.In Chapter 3,the thinning process of high-quality single-crystal two-dimensional germanium selenide material obtained by mechanical peeling using laser thinning technology is introduced.A single-layer two-dimensional germanium selenide material and its photoluminescence spectrum were successfully obtained at various temperature points.A 2 ?m thick silicon dioxide was conducted as substrate to obtain laser thinned?1.5 nm thick two-dimensional germanium selenide.At the same time,two-dimensional germanium selenide materials were prepared into optoelectronic devices by combining photolithography processes such as laser direct writing.Single-layer and few-layer two-dimensional germanium selenide devices were successfully prepared using laser thinning technology.A few layers of two-dimensional germanium selenide showed a broad photoluminescence spectrum similar to a single layer.The performance of a transistor with Schottky contact characteristics was measured in air and at room temperature.By modulating the holes and electrons of the device,bipolar characteristics were observed.The device had a switching ratio of 103 and a field-effect mobility of 4 cm2/(Vs).The light response was studied simultaneously as a function of illumination wavelength,power,and frequency.The few layers of germanium selenide devices responded to visible light with an illumination wavelength of up to 1400 nm and a rise(fall)time of 13?s(19 ?s),showing very broadband and fast light detection.In the fourth chapter,a small number of layers of germanium sulfide(?4.2 nm)field-effect-transistor devices were fabricated using the same mechanical lift-off and standard photolithographic processes as in the preparation of two-dimensional germanium selenide devices.A simple spin-coating method was used to spin-coat lead selenide quantum dots on a few layers of germanium sulfide devices to prepare hybrid heterostructure devices.Due to the transfer of charge from the lead selenide quantum dots to the surface of germanium sulfide,the photoluminescence intensity on the hybrid-structure decreased by 60%.At the light wavelength of 635 nm,the light response rate of the hybrid hybrid-structured device was doubled.On the hybrid-structure,the optical response bandwidth of lead selenide quantum dots extended from visible light to the near-infrared light band of 980 nm,with a response rate of 224 mA/W.The specific detection rates of the hybrid-structured devices are 808 nm And 980 nm increased by 39.5 times and 27.5 times.Under the same measurement conditions,compared with pure germanium sulfide devices,the enhancement of the carrier mobility of the hybrid-structured device reached 3 times.The concentration of lead selenide quantum dots at 1 mg/mL was optimized to obtain the highest photoresponse and carrier mobility of hybrid-structured devices.In Chapter 5,a two-dimensional material transfer system was constructed by combining the hot material graphene and the two-dimensional germanium sulfide materials.The preparation of graphene-germanium sulfide heterojunctions were explored and studied.Comparing the transformation of the wet and dry methods,a graphene-germanium sulfide heterojunction was successfully prepared and a simple characterization of the heterojunction was performed.Finally,we summarized the full text work and looked forward to the possible development direction of the materials I studied in the future.