MgxZn1−xO as a II–VI widegap semiconductor alloy

TLDR: In this article, a wide gap II-VI semiconductor alloy, MgxZn1−xO, was proposed for the fabrication of heteroepitaxial ultraviolet light emitting devices based on ZnO.

Abstract: We propose a widegap II–VI semiconductor alloy, MgxZn1−xO, for the fabrication of heteroepitaxial ultraviolet light emitting devices based on ZnO. The c-axis oriented MgxZn1−xO films were epitaxially grown by pulsed laser deposition on ZnO epitaxial films and sapphire (0001) substrates using ceramic targets. Solid solution films were prepared with Mg content up to x=0.33, achieving a band gap of 3.99 eV at room temperature. MgO impurity phase segregated at x⩾0.36. Lattice constants of MgxZn1−xO films changed slightly (∼1%), increasing in a axis and decreasing in c-axis direction with increasing x. These films showed ultraviolet photoluminescence at energies from 3.36 (x=0) to 3.87 eV (x=0.33) at 4.2 K.

Figures

FIG. 1. Mg content in the MgxZn12xO epitaxial films as a function of targe Mg content.

FIG. 4. Transmittance spectra of MgxZn12xO films measured at room tem perature. The inset shows the band gap (Eg) determined from the spectra assuming ana2}(hn2Eg) dependence, wherea andhn are the absorption coefficient and the photon energy, respectively.

FIG. 5. Photoluminescence~solid lines! and absorption spectra~dotted lines! of MgxZn12xO films (0<x<0.33). The spectra were taken at 4.2 The inset shows the luminescence peak position as a function of Mg con For the films with 0<x<0.14, He–Cd laser excitation~3.81 eV! was employed. For the films with 0.19<x<0.33, XeCl laser pulses~4.03 eV! were used. Solid triangles corresponded to the peaks due to phonon replica Downloaded 27 Oct 2004 to 130.34.226.195. Redistribution subject to AI