Elimination of Inclusions in (CdZn)Te Substrates by Post-grown Annealing
Post-grown annealing of (211) (CdZn)Te substrates has been used for elimination of Te and Cd inclusions with the objective of improving the yield of inclusion-free substrates for MBE growth of (HgCd)Te. Different annealing temperatures and Cd/Te overpressures were used to find the optimum annealing conditions. Te inclusions were significantly reduced by Cd-rich annealing at temperatures higher than 660°C, together with increasing the infrared transmittance at 10 µm to above 60%. Good crystalline quality was preserved after the annealing. Te-rich annealing at 700°C was found to be the optimum method for elimination of most of the Cd inclusions; infrared transmittance at 10 µm was suppressed by the annealing, however. Final Cd-rich annealing is recommended for infrared transmittance improvement.