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

The authors describe a gas-transport reaction method they recently developed using the compounds NH4Cl (Br, I) as transport agents. Using this method, they were able to grow semi-insulating cadmium telluride single crystals with 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 emission properties of homogeneous crystals at T=77 K and distinctive features of their photosensitivity spectra revealed that these material characteristics derive from the use of Cl, Br, and I as dopants. By illuminating their In-CdTe structures with linearly polarized light at oblique incidence, they generated induced photopleochroism, which was measured and used to determine 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 photodetectors of natural and linearly polarized light. (C) 1999 American Institute of Physics. [S1063-7826(99)00605-5].