Study Of Dislocation And Impurity In Sapphire And GaN

In this paper, the dislocation in Φ50mm CZ sapphire crystal had been observed by chemical etching with metallograph and SEM. Comparing the results which were obtained when the reagent and temperature and time varied ,we found the dislocation was displayed very clearly and accurately when we etch with KOH at 290℃ for fifteen minutes,which was the best condition.The defect and interface in sapphire and GaN were observed by AFM.We found that when the dislocation density in sapphire was lower thanl05/cm2, the dislocation density in GaN was 108~109/cm2and not linear with the dislocation in sapphire.The impurity of Mo in sapphire and GaN was measured by SEM XPS EPMA and UVF we found the Mo content in sapphire was 10-4,and the Mo content in GaN was lower than ppm. So it was concluded that low-cost Mo crucible is viable.