Electrical and Optical Properties of ZnO Bulk Crystals With and Without Lithium Grown by the Hydrothermal Technique

Document Type

Article

Publication Date

1-1-2014

Identifier/URL

40968927 (Pure)

Abstract

Lithium is usually added into the solution to improve ZnO hydrothermal growth; however, lithium doping affects the properties of the resulting crystals. Optical and electrical properties of hydrothermal ZnO bulk crystals without lithium, have been studied by photoluminescence and Hall-effect measurements. High quality ZnO crystals without lithium were grown in H2O/D2O and in NH3-H2O solutions. The crystals grown from H2O/D2O are conductive with resistivities of 0.6-0.7 Ωcm and mobilities of ~ 100 cm2/Vs, while lithium doped ZnO crystals typically have resistivities of ~ 103Ω-cm and mobilities of ~ 200 cm2/Vs, but can be varied from dozens to 1010 Ω-cm depending on lithium concentration. Lithium-free but nitrogen doped crystals grown in NH3-H2O solution have resistivities of 1×100 Ω-cm and sometimes show p-type conduction; the resistivity increases to ~ 1×108 Ω-cm after annealing at 600° C in air. Lithium and nitrogen co-doped ZnO crystals have resistivities of 108-1012 Ω-cm and are semi-insulating after annealling. Electronic irradiation also increases the ZnO resistivity. For lithium-doped samples, a 3.357 eV peak can be seen in the photoluminescence spectra. This is close to the donor-exciton peaks in indium-doped ZnO where 3.3586 eV and 3.357 eV were found on the C+ and C- faces, respectively. More studies are needed to identify lithium-related complexes (defects).

Comments

Presented at the 2014 SPIE OPTO Conference in San Francisco, California.

DOI

10.1117/12.2042344

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