MBE HgCdTe:A Challenge to the Realization of Third Generation Infrared FPAs

Some results on the molecular-beam epitaxial growth of HgCdTe focusing on the requirements of the 3rd generation infrared focal plane arrays are described.Good uniformity is observed over 75mm HgCdTe epilayers,and the deviation in cutoff wavelength is within 0.1μm at 80K.A variety of surface defects are observed and the formation mechanism is discussed.The average density of surface defects in 75mm HgCdTe epilayers is found to be less than 300cm-2.It is found that the surface sticking coefficient of As during HgCdTe growth is very low and is sensitive to growth temperature,being only ～1E-4 at 170℃.The activation energy of As in HgCdTe was determined to be 19.5meV,which decreases as (Na-Nd)1/3 with a slope of 3.1E-5meV·cm.The diffusion coefficients of As in HgCdTe of 1.0±0.9E-16,8±3E-15,and 1.5±0.9E-13cm2/s are obtained at temperatures of 240,380,and 440℃,respectively under Hg-saturated pressure.The MBE-grown HgCdTe is incorporated into FPA fabrications,and the preliminary results are presented.