MOCVD 两步生长法制备 GaN 量子点

The Fabrication of GaN Quantum Dots Using Metalorganic Chemical Vapor Deposition

报道了用金属有机化学气相沉积（ＭＯＣＶＤ）方法在蓝宝石衬底上成功地制备出ＧａＮ量子点。采用了５００℃低温沉积和１０５０℃高温退火的两步制备法制备出密度为５×１０８ｃｍ－２～６×１０９ｃｍ－２、直径约４０ｎｍ的ＧａＮ量子点。ＧａＮ量子点的密度和大小由原子力显微镜（ＡＦＭ）观察测得，并由制备温度和时间所控制。观察到ＧａＮ量子点仅在高温退火后生成，这可解释为由于低温沉积，最初的沉积层中的应变能得不到释放而成为具有较高能量的中间亚稳态相，高温退火使得应变能得到释放，生成ＧａＮ量子点。

GaN quantum dots have been successfuly fabricated on sapphire using metalorganic chemical vapor deposition (MOCVD) by two step method, including deposition at 500℃ and annealing at 1050℃. The density of GaN dots is from 5×10 8cm -2 to 6×10 9cm -2 , and the size is around 40nm in diameter. The density and the size of GaN dots are determined 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 annealling at high temperature. The phenomenon can be explained that the initial layer deposited at 500℃ is a high energy intermediate phase in which the large strain energy can not be relaxed because of the low temperature depositing.