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Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea*Unimo Photron Co., Ltd., Seoul 137-820, Korea(Received October 2, 2014)(Revised October 14, 2014)(Accepted October 17, 2014)Abstract We investigated defects and surface polarity in AlN and GaN by using wet chemical etching. Therefore, theeffectiveness and reliability of estimating the single crystals by defect selective etching in NaOH/KOH eutectic alloy havebeen successfully demonstrated. High-quality AlN and GaN single crystals were etched in molten NaOH/KOH eutecticalloy. The etching characteristics and surface morphologies were carried out by scanning electron microscope (SEM) andatomic force microscope (AFM). The etch rates of AlN and GaN surface were calculated by etching depth as a function ofetching time. As a result, two-types of etch pits with different sizes were revealed on AlN and GaN surface, respectively.Etching produced hexagonal pits on the metal-face (Al, Ga) (0001) plane, while hexagonal hillocks formed on the N-face.On etching rate calibration, it was found that N-face had approximately 109 and 15 times higher etch rate than the metal-face of AlN and GaN, respectively. The size of etch pits increased with an increase of the etching time and they tend tomerge together with a neighbouring etch pits. Also, the chemical mechanism of each etching process was discussed. It wasfound that hydroxide ion (OH |
