Effect Of Sapphire Substrate Etching On The Quality Of Gallium Nitride Epilayers

Ⅲnitrides materials have become one of the forefront research topics in semiconductor materials due to their successful application to fabricating of highly efficient optoelectronic devices. In this paper, GaN was grown on etched sapphire substrates in Metal Organic Chemical Vapor Deposition (MOCVD) reactor. And the performances of GaN grown on the etched substrates were compared with GaN on the ordinary substrates.Lots of experiments were practiced to fix on the etching time and etching temperature. The etching temperature is 265℃and etching time is 45~50min. And then GaN was grown on the etched sapphire by MOCVD. A model was built to analyse the mechanism of growing on the etched sapphire substrates.The performances of GaN layer prepared by this method were compared with the GaN layer under the same growth process but without etched substrate. The experimental results showed that the GaN epilayer with thinner full-width at half- maximum (FWHM), higher intensity value of X-ray diffraction,smoother surface and lower dislocation density was obtained using the etched substrate. The results of Raman showed that the stress in the epilayer was released. And the results of PL showed that the intensity of yellow-band and blue-band is related to the dislocation density. PL also showed that the luminescence property was improved by this method.The preparation of InGaN was also studied. The results of XRD showed four satellite peaks of quantum well structure. The full-width at half- maximum of PL is 26nm, which shows high quality of InGaN.