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.
The preparation of ohmic contact with high stability and low resistance is critical, and the quality of ohmic contact will directly affect the performance of devices as the efficiency, gain and switching speed. In this work, the I-V characteristic of the 4H-SiC devices under rapid thermal annealing and pulsed laser annealing were compared, the pulsed laser annealing process could obtain the lower ohmic contact resistant. The surface morphology, material composition, and elemental analysis were clarified by optical microscopy (OM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS), respectively. This research suggests that more Ni2Si and carbon vacancy can form at the interface under pulsed laser annealing.
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