An in situ technique based on diffuse reflectance spectroscopy to measure the thickness and temperature of CdTe films grown by molecular beam epitaxy on GaAs substrates is studied in this paper. A new model considering the interference of a thin film is set up to correct the previous errors observed in temperature measurements. A precise thickness parameter can be acquired by fitting the curves of the diffuse reflectance spectrum. This correction procedure is verified at the growth temperature of CdTe, which shows a nonoscillation result of the band edge thermometry. Compared with the thickness measured by an ex situ IR transmission spectrum, the thickness determined by using this model has an accuracy of less than 0.01 μm. This measurement can be used for precise in situ noncontact precise monitoring of growth temperature and thickness.

No abstract

Dual color detection is a major concept of the third generation infrared focal plane arrays sensors (FPAs) for increasing the demand of target identification. The performance of these detectors are largely relied on the growth capability of HgCdTe multilayered structure. This paper presents our preliminary results on growth of MW/LW two-color structure by using molecular beam epitaxy. The detector had NPpn architecture, with indium doped n-type bottom (window) layer and Hg-vacancy doped MW and LW p-type layers. The top n-type layer was ion implanted by using B + . The compositions (mole fraction x) of each layers and its gradient at the interfaces were measured by infrared transmission, SIMS and SEM. The In doping layer was analyzed by SIMS. The electrical properties of In doping layer were measured by Hall effects measurements. It was found that the structure obtained agreed well with the growth design. MW/LW two color detectors of a 64×64 format were fabricated by mesa delineation, and the optimum structure was also discussed.