Fig. 1. HgCdTe epitaxial material (a) transmission spectrum and theoretical fitting line, (b) longitudinal composition profile of Cd concentration

Fig. 2. Distribution of built-in electric field

Fig. 3. Sample A and sample B (a) longitudinal composition profile of Cd, (b) distribution of built-in electric field

Fig. 4. The schematic diagram of preparation position in epitaxial material

Fig. 5. The treatment process of sample （a）HgCdTe epitaxial layer，（b）passivating surface，（c）pasting onto sapphire，（d）removing substrate

Fig. 6. Normalized response spectra at 115 K, 215 K and 300 K (a) sample A, (b) sample B

Fig. 7. Cut-off wavelength with temperature （x=0.32）

Fig. 8. Built-in electric field generated by composition gradient at different temperatures

Fig. 9. Responsivity versus temperature in sample