Search

We have grown high-quality InxGa1-xN/GaN triple-quantum-well microdisks on LiAlO2 substrate by plasma-assisted molecular beam epitaxy. The InxGa1-xN/GaN microdisk with a hexagonal shape of oblique face 28o-angle off c-axis was achieved. The mechanism of the termination of awl-shaped growth and the growth rates of GaN-barrier and InxGa1-xN-well were evaluated and confirmed with the triple quantum wells. Based on the growth rates and 28o-angle geometric shape, one can control the finite size of InGaN/GaN microdisks by plasma-assisted molecular beam epitaxy.

We have grown a high-quality single-phase M-plane GaN on β-LiGaO2 (100) by plasma-assisted molecular beam epitaxy. The Hooke’s law for M-plane GaN was derived by a stress tenor transformation. From the analysis of M-plane GaN microstructure, the lattice strain of M-plane GaN along the [112¯0] and [0001] directions have been estimated. Based on the Hooke’s law, we calculated the ratio of anisotropic stress which was consistent with the ratio of thermal expansion-mismatch between GaN and LiGaO2 (100). We demonstrated that the thermal expansion mismatch was the major factor to degrade the quality of M-plane GaN on β-LiGaO2 (100).

InN hexagonal thin wurtzite disks were grown on γ-LiAlO2 by plasma-assisted molecular-beam epitaxy at low temperature (470oC). The ( 000 1 ¯ ) InN thin disk was established with the capture of N atoms by the β ¯ -dangling bonds of most-outside In atoms, and then the lateral over-growth of the In atoms were caught by the β ¯ -dangling bonds of the N atoms. From the analyses of high-resolution transmission electron microscopy, the lateral over-grown width was extended to three unit cells at [ 1 1 ¯ 00 ]InN direction for a unit step-layer, resulting in an oblique surface with 73o off c-axis.

The characterization of GaN microstructures grown by plasma-assisted molecular beam epitaxy on LiAlO2 substrate was studied by cathodoluminescence and photoluminescence measurements. We demonstrated that the cathodoluminescence from oblique semi-polar surfaces of mushroom-shaped GaN was much brighter than that from top polar surface due to the reduction of polarization field on the oblique semi-polar surfaces. It implies that the oblique semi-polar surface is superior for the light-emitting surface of wurtzite nano-devices.