Optical properties of three sectors in a zinc-oxide single crystal grown under hydrothermal process

We evaluated photoluminescence, radioluminescence, transmittance, and decay time at room temperature at each sector of zinc oxide (ZnO) single crystals grown utilizing the hydrothermal process. The −c-sector wafer, grown on the oxygen face of the c-plane seed crystal, has a short decay time and a high light yield and shows properties different from those of other sectors. We also fabricated a radiation sensor by combining the −c-sector chip cut from a wafer and a multipixel photon counter (MPPC). X-rays were detected using sensor with high sensitivity. At room temperature, typical decay time for the −c sector at the near band edge was 700 ps, and the range of relative light yield was thirty- to forty-times larger than that of the +c sector. Therefore, the properties of the −c-sector wafer at the near band edge will be suitable for high-speed radiation sensors in the near future.