Spin-splitting in an AlxGa1−xN/GaN nanowire for a quantum-ring interferometer

[[abstract]]The authors thank M. H. Gau, C. H. Hsieh, C. C Yang, R. Y. Su, and C. H. Chen for their assistance. The project was supported by National Science Council and Core Facilities Laboratory in Kaohsiung-Pingtung Area, Taiwan. The authors are also grateful to W. C. Mitchel and M. Mah for their help and AFOSR/AOARD, USAF for financial support under Grant No. FA4869-07-1-4022.[[abstract]]An Al0.18 Ga0.82 N/GaN heterostructure was used to fabricate a ballistic nanowire with a wire width of 200 nm by focused ion beam. We observed the beating Shubnikov-de Haas oscillations in the nanowire with a spin-splitting energy of (2.4±0.3) meV. Based on the results, we proposed a spin-Hall quantum-ring interferometer made of Alx Ga1-x N/GaN nanowires for spintronic applications. © 2008 American Institute of Physics.[[booktype]]紙

GaN and InN Hexagonal Microdisks

The high-quality GaN microdisks with InGaN/GaN quantum wells (QWs) and InN microdisks were grown on γ-LiAlO2 substrates by plasma-assisted molecular beam epitaxy (PA-MBE). The samples were analysed using scanning electron microscopy, X-ray diffraction, photoluminescence, cathodoluminescence and high-resolution transmission electron microscope. The characteristics of the GaN microdisks and InN microdisks were studied and the effect of growth temperature was evaluated

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

Wurtzite Effects on Spin Splitting of GaN/AlN Quantum Wells

A new mechanism (DeltaC1-DeltaC3 coupling) is accounted for the spin splitting of wurtzite GaN, which is originated from the intrinsic wurtzite effects (band folding and structure inversion asymmetry). The band-folding effect generates two conduction bands (DeltaC1 and DeltaC3), in which p-wave probability has tremendous change when kz approaches anti-crossing zone. The spin-splitting energy induced by the DeltaC1-DeltaC3 coupling and wurtzite structure inversion asymmetry is much larger than that evaluated by traditional Rashba or Dresselhaus effects. When we apply the coupling to GaN/AlN quantum wells, we find that the spin-splitting energy is sensitively controllable by an electric field. Based on the mechanism, we proposed a p-wave-enhanced spin-polarized field effect transistor, made of InxGa1-xN/InyAl1-yN, for spintronics application.Comment: 12 pages, 4 figures (total 16 pages

Anomalous k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures

We have confirmed the k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures. Anomalous beating pattern in Shubnikov-de Haas measurements arises from the interference of Rashba and Dresselhaus spin-orbit interactions. The dominant mechanism for the k-dependent spin splitting at high values of k is attributed to Dresselhaus term which is enhanced by the Delta C1-Delta C3 coupling of wurtzite band folding effect

Growth and Characteristics of High-quality InN by Plasma- Assisted Molecular Beam Epitaxy

The high-quality InN epifilms and InN microdisks have been grown with InGaN buffer layers at low temperatures by plasma-assisted molecular beam epitaxy. The samples were analyzed using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and photoluminescence. The characteristics of the InN epifilms and InN microdisks were studied, and the role of InGaN buffer was evaluated

Performance of the ATLAS trigger system in 2015

During 2015 the ATLAS experiment recorded 3.8fb−1 of proton–proton collision data at a centre-of-mass energy of 13TeV. The ATLAS trigger system is a crucial component of the experiment, responsible for selecting events of interest at a recording rate of approximately 1 kHz from up to 40 MHz of collisions. This paper presents a short overview of the changes to the trigger and data acquisition systems during the first long shutdown of the LHC and shows the performance of the trigger system and its components based on the 2015 proton–proton collision data

Advances in GaN Crystals and Their Applications

This special issue looks at the potential applications of GaN-based crystals in both fields of nano-electronics and optoelectronics. The contents will focus on the fabrication and characterization of GaN-based thin films and nanostructures. It consists of six papers, indicating the current developments in GaN-related technology for high-efficiency sustainable electronic and optoelectronic devices, which include the role of the AlN layer in high-quality AlGaN/GaN heterostructures for advanced high-mobility electronic applications and simulation of GaN-based nanorod high-efficiency light-emitting diodes for optoelectronic applications. From the results, one can learn the information and experience available in the advanced fabrication of nanostructured GaN-based crystals for nano-electronic and optoelectronic devices

Epitaxial growth of M-plane GaN on ZnO micro-rods by plasma-assisted molecular beam epitaxy

We have studied the GaN grown on ZnO micro-rods by plasma-assisted molecular beam epitaxy. From the analyses of GaN microstructure grown on non-polar M-plane ZnO surface ( 10 1 ̄ 0 ) by scanning transmission electron microscope, we found that the ZnGa2O4 compound was formed at the M-plane hetero-interface, which was confirmed by polarization-dependent photoluminescence. We demonstrated that the M-plane ZnO micro-rod surface can be used as an alternative substrate to grow high quality M-plane GaN epi-layers

Improvement of Mg-Doped GaN with Shutter-Controlled Process in Plasma-Assisted Molecular Beam Epitaxy

Mg-doped GaN was grown by plasma-assisted molecular beam epitaxy (PAMBE) on a Fe-doped GaN template substrate by employing a shutter-controlled process. The transition from n-type to p-type conductivity of Mg-doped GaN in relation to the N/Ga flux ratio was studied. The highest p-type carrier concentration in this series was 3.12 × 1018 cm−3 under the most N-rich condition. By modulating the shutters of different effusion cells for the shutter-controlled process, a wide growth window for p-type GaN was obtained. It was found that the presence of Mg flux effectively prevents the formation of structural defects in GaN epi-layers, resulting in the improvement of crystal quality and carrier mobility