Reduction of the Optical Absorption of Zinc Germanium Phosphide Via Post-Growth Thermal Anneal

Abstract

AbstractThis paper describes the reduction of the near-band-edge absorption of zinc germanium phosphide (ZGP) through thermal annealing. The effects of the annealing time, temperature and vapour atmosphere on the reduction of the optical absorption in the near infrared (NIR) region are reported. Results have shown that the optical absorption at 2µm is reduced by at least 50% upon thermal anneal of ZGP. The optimal annealing temperature was 600'C and the optimal annealing time ranged from 200 - 400 h. Annealing in vacuum yielded a larger reduction in the 2-µm optical absorption compared to annealing in the presence of additional zinc and phosphorus vapours. Re-annealing ZGP further reduced the absorption coefficient at 2-µm. However, the percentage decrease in the 2-µm absorption coefficient was much smaller compared to the first thermal anneal.