Status of MBE technology for the flexible manufacturing of HgCdTe focal plane arrays
A robust process has been developed for the reproducible growth of in-situ doped Hg1−xCdxTe:As alloys by molecular beam epitaxy. Net hole concentrations in excess of 5 x 1017 cm−3, with peak mobilities >200 cm2/Vs were measured in Hg0.74Cd0.26Te:As films. The p-type layers were twin-free and consistently exhibit narrow x-ray rocking curves (<40 arc sec). The reproducible growth of small lots of p-on-n LWIR detector structures has been established. For a typical lot consisting of 13 layers, the average x-value of the n-type base layer was 0.226 with a standard deviation of 0.003. The lateral compositional uniformity across a 2.5 cm × 2.5 cm wafer was × = +- 0.0006. High performance p-on-n LWIR diodes were fabricated that exhibited RoAo values (0-fov at 78K) as large as 350 Q cm2 at 10.4 µm.