Research of Structural and Optical Properties of MgZnO Films Annealed at Different Oxygen Partial Pressures

Structural and optical properties of MgZnO films were investigated by annealing in oxygen at different pressures. The crystalline quality of the annealed films improves with increasing annealing pressure. After annealing at 3.03×105Pa, the grain size became larger and oxygen content in the annealed films increased. This was attributed to the recrystallization of the films under high annealing pressure. However, a decreased oxygen content was found by annealing the films at 1.01×105or 2.05×10-3Pa. According to the defect levels and the relationship between photoluminescence spectra and annealing conditions, it was suggested that the emission peak located at 2.270 eV in photoluminescence spectra was related to interstitial oxygen (Oi) which will compensate the donor defects (Znior/and VO) and lead to the MgZnO film transforming into ap-type conduction under the annealing pressure of 3.03×105Pa.

Study on the Effect of ZnO Buffer Layer Thickness on the Properties of MgZnO Film

ZnO has recently attracted considerable attention due to its favorable properties such as the wider band gap (3.37eV) at room temperature, the large binding energy of excitons (60meV). These good photoelectric and piezoelectric properties [1-4] cause it has immensity space for developing at surface acoustic wave devices, light emitting diodes (LEDs) [5] , photodetectors [6], gas sensor and solar cells [7] etc. MgZnO has many similar properties to ZnO. Furthermore, the band gap of MgZnO is 3.3-4.0eV [9] due to the wider band gap of MgO (7.7eV [8]). In this paper, we report the characteristic of MgxZn1-xO films which were grown on c-plane sapphire with different thickness-ZnO buffer layers by MOCVD. By investigating the surface morphology, structural and optical properties, some dependences between properties of MgZnO films and the thicknesses of ZnO buffer layers can be found.