Spectral reflectivity monitoring of GaN growth

Summary form only given. The use of in situ spectral reflectance for monitoring the growth of GaN is described. By using this method to measure the growth of GaN nucleation layers at several temperatures and reactor pressures, the activation energy for the growth of the GaN nucleation layer versus temperature was determined to be 126 kJ/mole, independent of growth pressure over the range of 55 to 200 torr. During the growth of GaN, the nucleation layer is too thin to be measured using interferometry, but reflectivity measurements during the initial stages of high temperature GaN growth immediately following nucleation layer deposition probe the initial GaN surface morphology. While the final, thick GaN films are specular, the amount of time needed to create a smooth reflective growing surface can range from 100 to 1000 seconds. The required time is inferred from the development of good GaN surface reflectivity with intense interference fringes for the growth of a simple undoped GaN layer.