Effect of thermal annealing on the structural and electrical properties of HgTe/CdTe superlattices

Abstract

Rapid thermal annealing effects on the structural and electrical properties of the HgTe/CdTe superlattices grown on the Cd 0.96Zn 0.04Te substrates by molecular beam epitaxy have been investigated by double-crystal X-ray rocking curve (DCRC) and Van der Pauw Hall effect measurements. The sharp satellite peaks of the DCRC spectra measured on as-grown HgTe/CdTe superlattices show a periodic arrangement of the superlattice with high-quality interfaces. As the annealing time increases, the peak intensities corresponding to m=±1 of the DCRC spectra decrease dramatically. The average diffusion coefficient of the Hg in a HgTe/CdTe superlattice annealed at 220°C is approximately 10 −18 cm 2/s. After annealing, the results of the Hall effect measurements show that the carrier concentration and the mobility of the HgTe/CdTe superlattice are changed resulting from the formation of Hg vacancies and that the n-type HgTe/CdTe superlattice has converted to the p-type HgTe/CdTe superlattice with a high carrier concentration. These results indicate that the heterointerface of the HgTe/CdTe superlattice annealed at 220°C is significantly intermixed and that the monotonous variation of the intensity for the satellite peak in annealed HgTe/CdTe superlattice is attributed to a linear diffusion behavior.