Molecular Beam Epitaxy Growth And Device Research Of Middle Wave Quantum Well Infrared Detector (QWIP) Materials

Infrared detection technology has a broad and important application prospect in military,communications,medical and other aspects.?-?quantum well infrared detector?QWIP?with low cost,large area uniformity,good operation and good repeatability advantages,are widely used in monochrome,multicolor detection.At present,most of the work of quantum well infrared detectors focus on GaAs/AlGaAs material system.Due to the limitation of GaAs/AlGaAs quantum well band structure,its working wavelength is mainly located in the long-wave and very long-wave bands,and it is difficult to effectively cover the region of the medium-wave band?3-5?m?.Mid-wave infrared detectors are widely used in civil and military fields,such as optical communication,remote sensing,imaging and medical diagnosis.At present,InGaAs,HgCdTe,InSb and PbS are the main material systems for the preparation of mid-wave infrared detectors,among which InGaAs is the most widely usedInGaAs/AlGaAs QWIP with mid-wave response based on GaAs has become a global research hotspot.However,the fabrication of such devices is much more difficult than GaAs/AlGaAs QWIP.The control and regulation of In component is the key to grow the suitable wavelength range and good crystal quality.1.In this paper,we explored through the pre-process and used molecular beam epitaxy?Molecular Beam Epitaxy,MBE?growth system to grow 1.8 nm?sample A?,2.1nm?sample B?and 2.3 nm?sample C?In_0.35Ga_0.65As/Al_0.34Ga_0.66As mid-wave quantum well materials.The growth temperature of In_0.35Ga_0.65As well layer is 480?,and that of Al_0.34Ga_0.66As barrier layer is 580?.The properties of quantum well?QW?materials with different well widths were characterized by scanning electron microscopy?SEM?,X-ray diffraction?XRD?and photoluminescence?PL?.According to the diffraction spectrum at2?of XRD,it can be seen that the X-ray swing curve has more satellite peaks,and the whole satellite peak line width is smaller and the peak strength is stronger,which indicates that the material lattice quality is good and should be properly controlled.The growth thickness of quantum well material was measured by SEM,The results show that the 20cycles of quantum well have good repeatability and stable growth conditions.The PL spectra of the three samples were tested respectively,it is found that the PL spectrum of the quantum well is significantly redshifted as the well widens2.The effect of different transition modes on device performance was studied.In this paper,the QWIP transition mode is adjusted by changing the well width to affect the performance of the QWIP device.We prepared three quantum well infrared detectors,Sample A,Sample B,and Sample C.Experiments show that:?1?the parabolic trend of the black body response current of the Sample A device does not change significantly with the bias voltage,while the black body response current response of the Sample C device changes with the bias voltage to a parabolic trend.?2?Using Fourier spectrometer to test the spectral response of devices Sample A,Sample B,and Sample C at 77 K liquid nitrogen temperature.The test results showed that the peak response wavelength of the three samples was 4.16?m,4.10?m and 4.07?m,the half-peak width was 0.66?m,0.58?m and 0.49?m,and the spectral peak response was0.12 A/W,0.11 A/W and 0.10 A/W,respectively.As the well width widens,the transition energy levels change and the peak response wavelength blue shift;In response to the narrowing of the half-peak width,the transition mode changes from the bound state to the quasi-continuous state?B-QC?to the bound state to the quasi-bound state?B-QB?.?3?The dark current test results show that Sample A has the largest dark current at different temperatures,and Sample C has the smallest dark current.When the dark current is the same,the device with the well width of Sample C is subjected to greater bias,which further indicates that the transformation of B-QC to B-QB.The results show that the well width changes the energy level and the response wavelength,the change of transition mode leads to the change of half-peak width.Our results show that the B-QB transition mode and the B-QC mode can be converted by changing the well width in mid-wave quantum well infrared detector,and compared with B-QC mode,the device based on B-QB transition mode can effectively reduce the device dark current.