Optimal Design And Experimental Vertification Of HgCdTe Infrared Focal Plane Arrays Detector

Under the rapid development of high-performance infrared focal plane array detectors, next-generation HgCdTe infrared detectors will not only need to design and optimize the new-structure detectors but also need to develop its special and integrated technology. In this thesis, two-color, photon trapping and Si-substrate long-wavelength HgCdTe infrared detectors were designed and optimized, using Crosslight Technology Computer Aided Design Software Apsys. In addition, the application of atomic layer deposition（ALD） on steep-structure HgCdTe infrared detectors and bulk and interface properties of ALD passivants were investigated. The main results are summarized as follows.1. Design and optimization of new-structure HgCdTe infrared detectors.Firstly, structural design of HgCdTe n⁺-p₁-P₂-P₃-N⁺ medium-wave/long-wave two-color detector functioning in simultaneous mode was carried out. Simulation indicated that two-color detector with MW-to-LW and LW-to-MW spectral crosstalk less than 2% was achieved by optimizing the compositional barrier. Secondly, n+-on-p mid-wavelength detector integrated with photon trapping structures was investigated. Photon trapping detector with lowered dark current and no appreciable decrease in quantum efficiency was demonstrated by adjusting the size and distribution of the vertical-cavity within the pixel. Finally, a new p-on-N+ HgCdTe heterojunction long-wavelength device on Si substrate was designed. Simulation indicated that the structure not only effectively suppressed the interface recombination of photo-generated carrier to improve the detectivity of the response band significantly but also adjusted the cut-on wavelength by changing the composition of N+ layer to control the spectral width of the response band.2. Passivation properties of atomic layer deposition Al₂O₃ film.In this work, 65℃ low-temperature deposition of ALD-Al₂O₃ film on HgCdTe was achieved; ALD-Al₂O₃ film on steep-structure HgCdTe infrared detector was uniform and compact; HgCdTe MIS devices and photodiodes passivated with Al₂O₃ film was successfully fabricated; Experimental results indicated that dielectric constant of Al₂O₃ film was about 7.0 and its surface recombination velocity, fixed and slow charge density was comparable to CdTe/ZnS film; Passivation effect of ALD-Al₂O₃ film was improved by 180℃ hight-temperature annealing treatment, but C-V characteristics of MIS devices and R-V characteristics of photodiodes decreased gently after 75℃/48 h baking treatment.3. Passivation properties of atomic layer deposition ZnS film.In this work, 65℃ low-temperature deposition of ALD-ZnS film on HgCd Te was achieved; ALD-ZnS film on steep-structure HgCdTe infrared detector was uniform and compact; HgCdTe MIS devices and photodiodes passivated with ZnS film was successfully fabricated; Experimental results indicated that dielectric constant of Al₂O₃ film was about 6.0 and its fixed and slow charge density was comparable to CdTe/ZnS film, but trap charge density was more than an order of magnitude; Through HgCdTe surface treatment experiment of traditional ZnS pre-coverage, it was demonstrated that unexpected passivation effect of ZnS film had a direct relation with HgCdTe/Zn S interface state.