Fabrication of GaN quantum dots using metal-organic chemical vapor deposition

GaN quantum dots have been successful fabricated on sapphire by using metallorganic chemical vapor deposition (MOCVD) by two-step method, including deposition at 500 °C and annealing at 1050 °C. The density and the size of GaN dots are determined by using an atomic force microscope (AFM), and they are controllable by changing the temperature and the duration of the depositing and the annealing. GaN dots are formed only after annealing at high temperature. The phenomenon can be explained like this: the initial layer deposited at 500 °C is a high energy intermediate phase in which the large strain energy can not be relaxed because of the low temperature depositing.