In this work, the evolution of the InGaN layer growth on the ridge shaped GaN was studied. A mass transport model was presented to simulate the epitaxy process of the InGaN layer. The model consisted of two consecutive components, gas-phase diffusion process and surface diffusion process. The mean lifetime of adatoms on epitaxial surface was associated with their reaction rate in this model. An InGaN layer on ridge shaped GaN, including (0002) and {112¯2} facets, was grown by metal organic chemical vapor deposition to confirm the mass transport model. Gradient indium content distribution and inhomogeneous thickness of the InGaN layer were observed. Simulation of the InGaN layer growth process was performed by finite difference method with the mass transport model. By analyzing the results from calculations and experiments, the origins of the InGaN layer characteristics were attributed to the two diffusion components in the growth process. Surface diffusion resulted in the inhomogeneous thickness and gas-phase diffusion chiefly led to the gradient indium content. In addition, the adatoms reaction rate on epitaxial surface determined their mean lifetime as speculated by the analysis. The demonstration of the growth process of InGaN layer offers valuable insight in obtaining high efficiency white light emitting diodes by selective area growth technology.
A method of reducing threading dislocation (TD) density in AlN epilayers grown on sapphire substrate is reported. By introducing an AlN buffer layer grown by a pulsed atomic-layer epitaxy method, TDs in epitaxial AlN films were greatly decreased. From transmission electron microscopic images, a clear subinterface was observed between the buffer layer and the subsequently continuous grown AlN epilayer. In the vicinity of the subinterface, the redirection, annihilation, and termination of TDs were observed. The increase in lateral growth rate accounted for TD redirection and annihilation in the AlN epilayer. Strain variation between the two regions resulted in the termination of TDs owing to the dislocation line energy minimization.
In this paper we present the first report of the study of the characteristics of In0.53Gs0.47As/InP modulation-doped heterostructures grown by liquid-phase epitaxy. Electrical properties were studied by Hall and Shubnikov-de Haas Measurements. A series of doping levels in the InP layer was used to investigate the dependences of mobility and sub-band configuration on sheet carrier density. Mobility enhancements were observed at low temperatures according to Hall measurements. Enhanced electron mobilities were as high as 62000, 60200 and 7410 cm2/Vs at 10, 77 and 300 K, respectively. These are comparable to those obtained by other epitaxial techniques, which indicates that liquid-phase epitaxy is capable of growing high-quality In0.53Ga0.47As/InP heterojunctions.
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