Optimization of Ternary InxGa1-xN Quantum Wells on GaN Microdisks for Full-Color GaN Micro-LEDs.

Red, green, and blue light InxGa1-xN multiple quantum wells have been grown on GaN/γ-LiAlO2 microdisk substrates by plasma-assisted molecular beam epitaxy. We established a mechanism to optimize the self-assembly growth with ball-stick model for InxGa1-xN multiple quantum well microdisks by bottom-up nanotechnology. We showed that three different red, green, and blue lighting micro-LEDs can be made of one single material (InxGa1-xN) solely by tuning the indium content. We also demonstrated that one can fabricate a beautiful InxGa1-xN-QW microdisk by choosing an appropriate buffer layer for optoelectronic applications.

Growth and Characterization of M-Plane GaN Thin Films Grown on γ-LiAlO2 (100) Substrates.

M-plane GaN thin films were grown on LiAlO2 substrates under different N/Ga flux ratios by plasma-assisted molecular beam epitaxy. An anisotropic growth of M-plane GaN was demonstrated against the N/Ga flux ratio. As the N/Ga flux ratio decreased by increasing Ga flux, the GaN surface trended to a flat morphology with stripes along [11[Formula: see text]0]. According to high-resolution X-ray diffraction analysis, Li5GaO4 was observed on the interface between GaN and LiAlO2 substrate. The formation of Li5GaO4 would influence the surface morphology and crystal quality.

Spin-splitting calculation for zincblende semiconductors using an atomic bond-orbital model.

We develop a 16-band atomic bond-orbital model (16ABOM) to compute the spin splitting induced by bulk inversion asymmetry in zincblende materials. This model is derived from the linear combination of atomic-orbital (LCAO) scheme such that the characteristics of the real atomic orbitals can be preserved to calculate the spin splitting. The Hamiltonian of 16ABOM is based on a similarity transformation performed on the nearest-neighbor LCAO Hamiltonian with a second-order Taylor expansion k at the Γ point. The spin-splitting energies in bulk zincblende semiconductors, GaAs and InSb, are calculated, and the results agree with the LCAO and first-principles calculations. However, we find that the spin-orbit coupling between bonding and antibonding p-like states, evaluated by the 16ABOM, dominates the spin splitting of the lowest conduction bands in the zincblende materials.

Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE.

We have investigated the structure of non-polar GaN, both on the M - and A-plane, grown on LiGaO2 by plasma-assisted molecular beam epitaxy. The epitaxial relationship and the microstructure of the GaN films are investigated by transmission electron microscopy (TEM). The already reported epi-taxial relationship and for M -plane GaN is confirmed. The main defects are threading dislocations and stacking faults in both samples. For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1. In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

Current development and patents on high-brightness white LED for illumination.

In this paper, we reviewed the current development and patents for the application of high-brightness and high-efficiency white light-emitting diode (LED). The high-efficiency GaN nanostructures, such as disk, pyramid, and rod were grown on LiAlO(2) substrate by plasma-assisted molecular-beam epitaxy, and a model was developed to demonstrate the growth of the GaN nanostructures. Based on the results, the GaN disk p-n junction was designed for the application of high brightness and high efficiency white LED.

P-wave-enhanced spin field effect transistor and recent patents.

P-wave-enhanced spin field-effect transistor made of AlGaN/GaN heterostructure was designed for the spintronic devices operated at high power and high temperature. The operation theory is based on the spin-polarized field-effect transistor designed by Datta and Das [Appl. Phys. Lett. 56, 665 (1990)]. The mechanism of the p-wave enhancement in AlGaN/GaN heterostructure was investigated. The recent development and related patents in the spin-polarized field-effect transistor were reviewed. In particular, we will focus on the recent patents which could enhance p-wave probability and control of spin precession of 2DEG in the AlGaN/GaN transistor structure.