应对第三代红外焦平面技术挑战的HgCdTe分子束外延

叙述了围绕第三代红外焦平面的需求所进行的HgCdTe分子束外延的一些研究结果.75mm HgCdTe薄膜材料的组分均匀性良好,80K下截止波长偏差为0.1μm.对所观察到的HgCdTe表面缺陷成核机制进行了分析讨论,获得的75mm HgCdTe材料平均表面缺陷密度低于300cm-2.研究发现As的表面黏附系数很低,对生长温度十分敏感,在170℃下约为1×10-4.计算表明,As在HgCdTe中的激活能为19.5meV,且随(Na∑Nd)1/3的增大呈线性下降关系,反比系数为3.1×10-5meV·cm.实验发现Hg饱和蒸汽压下,对应不同的温度240,380,440℃,As在HgCdTe中的扩散系数分别为(1.0±0.9)×10-16,(8±3)×10-15,(1.5±0.9)×10-13cm2/s.采用分子束外延生长的HgCdTe材料已用于红外焦平面探测器件的研制,文中报道了一些初步结果.

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 0.1μat 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 ～ 1 × 10-4 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 3.1 × 10-5 meV · cm. The diffusion coefficients of As in HgCdTe of 1.0 ± 0.9 × 10-16 ,8 ± 3 × 10-15 ,and 1.5 ± 0.9 × 10-13cm2/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.