| Light is an important carrier for transmitting information,and the emergence of photodetectors provides a new method for humans to record and transmit signals.As one of the important research directions of photoelectric detection,the dual-band detector can suppress the influence of complex background on photoelectric detection and improve the detection accuracy,and has important application value in the fields of military,security,remote sensing and so on.The discovery of new materials and new mechanisms is the driving force behind the development of photodetectors.In recent years,the emergence of low-dimensional materials,especially the special photoelectric properties determined by their quantum confinement properties,has injected new vitality into the field of infrared detection.Graphene is an ideal photoelectric detection material.Due to its high carrier mobility,graphene can be used as a high-speed transmission channel for photo-generated carriers,and its zero band gap characteristic allows its absorbable spectral range to cover the entire ultraviolet to far infrared band,Good processability makes it easy to form van der Waals contact with traditional semiconductor materials to build a graphene stack structure;however,the lower absorption rate of graphene has caused significant limitations to its responsivity.Although the researchers proposed to increase the responsiveness by increasing the gain,but usually at the expense of response speed.To this end,based on the stacked device structure of graphene and high mobility materials,this paper studied the photoelectric conversion and carrier transport mechanism in above device,improve responsiveness and response speed at the same time;developed the graphite alkenyl sandwich structure dual-band detector and introduces two-band gains,proposes a new dual-band signal extraction method,and explores the improvement of detection performance based on this method.The specific research results are as follows:(1)In view of the problem that the current graphene stacked photodetector devices often increase the gain at the expense of response speed,an in-depth study of the effects of material mobility and carrier trap concentration on the gain in the stacked structure reveals the photogeneration in different stacked structures carrier generation and transport mechanism,proposed high-mobility InGaAs and graphene stacked photoconductive near-infrared detector,studied graphene transfer and device preparation process optimization methods,reduced factors limiting graphene mobility performance,constructed The back electrode voltage regulation mechanism finally realized that the InGaAs/graphene device’s near-infrared responsivity was improved by 14.7 times than the intrinsic InGaAs device,reaching 7.66 A/W,and the response speed was increased by 120%.(2)Aiming at the problem that the current traditional dual-band detector signal extraction requires a complex external optical system or a special internal electrode design to apply different bias voltages,this paper studies the response characteristics of different materials in the stacked dual-band detector,and proposes a reasonable Choose materials to have obvious difference in response speed in different bands,study the device structure and optimize the thickness of the upper wide bandgap material in the laminated structure,so as to realize the absorption of short and long waves in partitions,and cooperate with the light source signal switching frequency modulator to achieve different band A new method of dual-band detection signal extraction based on signal frequency extraction.In order to solve the problem of insufficient photoelectric gain in current low-dimensional material dual-band detectors,this study inserts graphene into the laminated dual-band detection material to form a sandwich structure,and achieves the simultaneous introduction of photoelectric gain for both bands.A dual-band detector with Ge/graphene/CdS structure was proposed to verify the feasibility of the new signal extraction method,revealing the mechanism of photo-generated carrier generation and transport in the device,and analyzing the formation mechanism of the gain to achieve 450 nm With 1550 nm wavelength laser,the photoelectric gain of the device is 7.8×10~7 and 4.7×10~3,respectively.(3)Based on the research of dual-band gain introduction and signal frequency division extraction,combined with the research results of InGaAs/graphene stacked devices with high gain and fast response in this paper,and analyze the factors that limit the improvement of stacked dual-band detection performance,InGaIn/Graphene/CdS dual-band detection devices are proposed to further improve device performance and verify the universality of signal extraction methods.The two heterojunctions of InGaAs/graphene and graphene/CdS share a high-speed carrier transmission channel.The two-band signal collection is realized in a photoconductive structure,which avoids the energy loss when the optical signal penetrates the electrode and improves the external quantum efficiency.In terms of performance improvement,under 450 nm wavelength incident light,InGaAs/Graphene/CdS dual-band detectors have a 17%increase in responsiveness compared to Ge/Graphene/CdS dual-band detectors,while increasing the response speed:rising edge And the falling edge time were shortened by 75%and44%,respectively;at 1550 nm wavelength incident light,the responsivity increased by32%,the rising edge was unchanged,and the falling edge time was shortened by 62%.The laminated structure in this study provides a new solution for dual-band detection. |
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