Impurity band in magnesium-doped GaN layers grown by metalorganic chemical vapor deposition

InGaN/GaN quantum well light emitting diodes (LEDs) were grown with p-GaN layers of varied Mg impurity content. As the concentration of Mg impurity increases, the hole concentration increases up to a critical Mg impurity density and then decreases with further increase of the impurity. In this work, it is proposed that the accepters form the impurity band and that the band behavior with Mg content variation is attributed to the properties of the p-GaN layer and the p-layer effect on the I-V characteristics of LED.