Fabrication And Characterization Of 12.5?m Long Wave Infrared Detector

In this paper,the characteristics of the dark current of the long wave HgCdTe infrared detector prepared by different technical routes are studied.In view of the large surface leakage of the HgCdTe device,the annealing process of the CdTe passivating layer on the electron beam growth of the Au doped P type HgCdTe material under vacuum is proposed,and the composition of the component is formed at the CdTe/HgCdTe interface.The effect of surface charge on the internal of HgCdTe is reduced,and the process is systematically studied.The device is prepared by this process.The variable area diode array and the structure of the gate controlled diode are designed to characterize the effect of the process on the performance of the device.In addition,in order to better characterize the performance of long wave HgCdTe infrared detector,a system using Fourier spectrometer to test the spectrum of focal plane devices has been built,and good results have been obtained.Provides a practical and theoretical basis for the preparation of large-scale long-wavelength HgCdTe infrared detector.The main contents are as follows:1.Research on dark current of different process routesThe leakage current of the mercury vacancy n-on-p planar junction device is mainly produced by the smaller reverse and zero bias current,and the direct tunneling current plays a leading role in the leakage current.Through the study of the variation of the dark current with the carrier concentration of the Au doped n-on-p planar junction device,it is found that the carrier concentration increases with the material carrier concentration.The leakage current near the smaller reverse and zero bias is mainly caused by the compound current and the diffusion current,which is dominated by the compound current.The direct tunneling current increases significantly with the increase of the carrier concentration,and the direct tunneling current is smaller in the dark current of the in-situ doped p-on-n mesa junction device.The device is seriously affected by the leakage of the surface.2.CdTe/HgCdTe interdiffusion annealing process.The interdiffusion annealing process of doped Au doped P type HgCdTe material covered by CdTe in vacuum is studied systematically.It is found that increasing the growth temperature of electron beam evaporation can effectively improve the densification of CdTe films.When the growth temperature is less than 175?,the SEM images of CdTe grown by electron beam evaporation are columnar structures.After annealing,the carrier concentration is only related to the final annealing temperature.It has no relationship with the process of temperature change during the annealing process.The carrier concentration after annealing at 210²40?is about 2.0×10¹⁶cm^-3,and about 5.5×10¹⁶cm^-3 at 260³00?.The annealing process does not change the distribution of Au in HgCdTe.The annealing effect of 210²40?on the Cd and Hg components of CdTe/HgCdTe is not obvious.The diffusion of Cd and Hg can be found at 260³00?,and the diffusion coefficient can be expressed asD?7?x?8??28?0.55?e^-3.0x.3.Fabrication of long wavelength HgCdTe infrared detector.The HgCdTe long wave infrared detectors were fabricated by the annealing process,and a series of test structures were prepared.The effects of the CdTe/HgCdTe interface Cd and the Hg component in the annealing process on the performance of the device were analyzed.The fabrication process of annealed materials is studied.By fitting the dark current,the slow gradient concentration CdTe/HgCdTe can obviously suppress the tunneling current,thereby improving the reverse dynamic impedance.By test of the variable area diode array,the leakage current of the surface after annealing treatment is obviously suppressed.1/f noise is obviously suppressed,and its noise level is close to white noise.After annealing,the quality of the passivation layer CdTe and HgCdTe is improved,and it does help to improve the stability of the device.The baking temperature of 48h can be raised from 75?to 85?.4.A Fourier transform spectrometer is used to test the spectrum of focal plane devices.The test range of the system is 400-15000cm^-1,which can cover part of visible light band.The highest spectral resolution in this paper is 4cm^-1,which can increase the spectral resolution by increasing the step number,and can make the measured spectrum more detailed.The advantage of the system is that it can simultaneously measure the spectrum of all photosensitive elements of the whole focal plane device.Fourier transform spectroscopy is used to analyze a series of errors,and the effects of white noise,phase errors and various kinds of pulse errors on spectral noise are analyzed.The calculation results show that 1%of the white noise can produce about 4%of the measurement spectrum,the pulse noise of the single 1/10 interference amplitude,the RMS error of the spectrum is 1.6%,the 10 times 1/10 interference amplitude pulse noise,the RMS error of the spectrum is 7.4%,the phase error is the smallest to the spectrum,and the maximum root mean square error is not higher than 0.011%.The errors are proportional to the amplitude of noise.