Pointed Cone Shaped Light-Emitting Diodes Based on ZnO/GaN Wafer Bonding

We report on pointed cone shaped blue light-emitting diodes(LEDs) based on ZnO and GaN wafer bonding. After wafer bonding of an n-type ZnO substrate to a III–nitride LED wafer, sapphire was removed and n- and p-pads were formed on the same side. Pointed hexagonal ZnO cone was formed by a selective chemical etching method. The [...]

February 11th, 2019|

Numerical simulation of terahertz-wave propagation in photonic crystal waveguide based on sapphire shaped crystal

Terahertz (THz) waveguiding in sapphire shaped single crystal has been studied using the numerical simulations. The numerical finite-difference analysis has been implemented to characterize the dispersion and loss in the photonic crystalline waveguide containing hollow cylindrical channels, which form the hexagonal lattice. Observed results demonstrate the ability to guide the THz-waves in multi-mode regime in [...]

January 28th, 2019|

Internal transitions of acceptors confined in delta-doped GaAs/AlAs multiple quantum wells

We have investigated experimentally and theoretically the influence of the quantum confinement effect on internal transitions of shallow beryllium acceptors in both bulk GaAs and a series of delta-doped GaAs/AlAs multiple quantum well samples with well width ranging from 30 to 200 Å. A series of beryllium delta-doped GaAs/AlAs multiple-quantum wells with the doping at [...]

January 22nd, 2019|

Temperature-independent slow carrier emission from deep-level defects in p-type germanium

In the deep-level transient spectroscopy (DLTS) spectra of the 3d-transition metals cobalt and chromium in p-type germanium, evidence is obtained that hole emission from defect levels can occur by two parallel paths. Besides classical thermal emission, we observed a second, slower and temperature-independent emission. We show that this extra emission component allows determining unambiguously whether [...]

January 14th, 2019|

Multiple-scattering effects in Ga K-edge extended x-ray absorption fine structure spectra of GaP, GaAs and GaSb semiconductor compounds

The dependence of Ga K-edge multiple-scattering extended x-ray absorption fine structure (MS-EXAFS) effects on the nearest neighbours in GaP, GaAs and GaSb semiconductor compounds with the zinc blende structure has been comprehensively investigated by considering the coordination environment within the first three shells around the Ga atoms. It is revealed that in the case of GaP with a light element as the first neighbour of the Ga absorber, the MS-EXAFS effects are negligibly weak with respect to the single-scattering (SS) contribution. For GaAs and GaSb compounds with heavier elements as the first neighbour of the Ga absorber, the MS effects become increasingly important and are dominated by a triangular double-scattering path DS2 ( ). The EXAFS contribution of the DS2 path destructively interferes with that of the second shell single-scattering path (SS2), with the amplitude ratio of DS2 to SS2 rising from 7% for GaP to 25 and 70% for GaAs and GaSb, respectively. This indicates that the second shell peak magnitude for these compounds is increasingly damped by the MS effects as the first nearest neighbour goes from P to Sb. Based on these results, we present a generalized and simplified high-shell MS-EXAFS analysis method for compounds with the open structure of zinc blende. Source:IOPscience For more information, please visit our website:http://www.substratewafer.com, send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com

January 8th, 2019|

Carrier lifetime and breakdown phenomena in SiC power device material

Recent progress and current understanding of carrier lifetimes and avalanche phenomena in silicon carbide (SiC) are reviewed. The acceptor level of carbon vacancy (V C), called the Z 1/2 center, has been identified to be the primary carrier lifetime killer in SiC. The V C defects can be eliminated by the introduction of excess carbon [...]

January 3rd, 2019|

White light emission of monolithic InGaN/GaN grown on morphology-controlled, nanostructured GaN templates

We demonstrated an InGaN/GaN-based, monolithic, white light-emitting diode (LED) without phosphors by using morphology-controlled active layers formed on multi-facet GaN templates containing polar and semipolar surfaces. The nanostructured surface morphology was controlled by changing the growth time, and distinct multiple photoluminescence peaks were observed at 360, 460, and 560 nm; these features were caused by [...]

December 25th, 2018|

Simulation Research on Micro Contact Based on Force in Silicon Wafer Rotation Grinding

Silicon wafer rotation grinding with cup type diamond wheel is a typical ultra precision grinding process. In this paper, a simulation model based on force for micro contact between wheel micro unit and silicon wafer is established from the stable ductile grinding process. Micro contact process in grinding is simulated using the nonlinear explicit finite [...]

December 17th, 2018|

Theoretical considerations on efficiency degradation due to thermal effect in a planar GaN-based LED with a GaN substrate

In this paper, using a fully-coupled, three-dimensional electro-thermal device simulator, we study the mechanism of efficiency degradation at high current operation in planar GaN-based light emitting diodes (LED). In particular, the improvement of the efficiency degradation using thicker conductive GaN substrates has been demonstrated. First, it is found that local Joule heating inside thin conductive [...]

December 11th, 2018|

An optical study of the D—D neutron irradiation-induced defects in Co- and Cu-doped ZnO wafers

Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped (1 × 1014, 5 × 1016, and 1 × 1017 cm−2) and Cu-doped (5 × 1016 cm−2) ZnO wafers irradiated by D—D neutrons (fluence of 2.9 × 1010 cm−2) have been investigated. After irradiation, the Co or Cu metal and oxide clusters in doped ZnO wafers are [...]

December 4th, 2018|