Effect of Annealing in an Atomic Oxygen Atmosphere on Photoluminescent and Electrical Properties of Hydrothermal ZnO Single Crystals

Abstract

The effect of annealing in an atomic oxygen atmosphere on the photoluminescent and electrical properties of highquality ZnO single crystals grown by the hydrothermal method was studied. The spectrum of as-prepared ZnO samples exhibited a series of narrow lines in the UV region and long-wavelength emission peaking at 510 nm. The nature of the observed bands was discussed. Hall effect measurements indicated that the dominant donor in as-prepared ZnO samples had ionization energy E_D = 67 meV and concentration N_D = 3.6∙10¹⁸ cm^–3. The ND value decreased to 3.7∙1017 cm^–3, while the E_D value did not change after heat treatment in an atomic oxygen atmosphere at 600–700°C for 1 h. A ZnO single crystal annealed at 800°C showed p-type conductivity with an acceptor concentration N_A = 2.7∙10¹⁶ cm^–3.