Optoelectronic effects in semi-insulating CdTe single crystals and structures based on them

The authors describe a gas-transport reaction method they recently develope d using the compounds NH4Cl (Br, I) as transport agents. Using this method, they were able to grow semi-insulating cadmium telluride single crystals w ith carrier concentrations p=10(8)-10(10)cm(-3) at T=300 K. These crystals were used to fabricate In-CdTe surface-barrier structures with peak voltaic photosensitivities of similar to 10(5) V/W. Their investigations of the em ission properties of homogeneous crystals at T=77 K and distinctive feature s of their photosensitivity spectra revealed that these material characteri stics derive from the use of Cl, Br, and I as dopants. By illuminating thei r In-CdTe structures with linearly polarized light at oblique incidence, th ey generated induced photopleochroism, which was measured and used to deter mine the refraction index of the material, which is found to be n=2.8. The paper concludes with a discussion of how these structures can be used as ph otodetectors of natural and linearly polarized light. (C) 1999 American Ins titute of Physics. [S1063-7826(99)00605-5].