| Popis: |
The annealing behavior of Hg1CdTe layers, grown by the conventional Organometallic Vapor Phase Epitaxy (OMVPE) , is reported. As grown layers, which are p-type with a concentration around 4 x 10'6/cm3 of mercury vacancies, become light p-type with carrier concentrations around 1-2x 10'5/cm3 after Hg saturated annealings at temperatures in the range of 200-230°C. These conditions, usually sufficient for the complete annealing of bulk Hg1_CdTe, to n-type, are thus inadequate for OMVPE grown epilayers. The as grown layers are converted to n-type with a carrier concentration of approximately 5 x 10'4/cm3 by a higher temperature anneal at 290°C, followed by a low temperature anneal at 220°C. Hall effect measurements were made under variable temperature as well as variable magnetic field conditions. Bulk carrier concentrations and mobilities were evaluated by considering the effect of the surface inversion/accumulation layer on the Hall data. It is proposed that ptype conduction in the partially annealed layers is due to the persistence of vacancies in the Hg1_CdTe layer, which are not completely annihilated during the low temperature anneal. Conversion to n-type is probably due to residual donor impurities in the as grown Hg1_CdTe layer. |
