This report presents the results of steady-state and time-resolved luminescence measurements performed on suspensions of nanocrystalline ZnO particles of different sizes and at different temperatures. In all cases two emission bands are observed. One is an exciton emission band and the second an intense and broad visible emission band, shifted by approximately 1.5 eV with respect to the absorption onset. As the size of the particles increases, the intensity of the visible emission decreases while that of the exciton emission increases. As the temperature decreases, the relative intensity of the exciton emission increases. In accordance with the results presented in a previous paper, we assume that the visible emission is due to a transition of an electron from a level close to the conduction band edge to a deeply trapped hole in the bulk ( ) of the ZnO particle. The temperature dependence and size dependence of the ratio of the visible to exciton luminescence and the kinetics are explained by a model in w...

The kinetics of the radiative and nonradiative processes in nanocrystalline ZnO particles upon photoexcitation

A nitride semiconductor device including a light emitting device comprises a n-type region of one or more nitride semiconductor layers having n-type conductivity, a p-type region of one or more nitride semiconductor layers having p-type conductivity and an active layer between the n-type region and the p-type region. In such devices, there is provided with a super lattice layer comprising first layers and second layers which are nitride semiconductors having a different composition respectively. The super lattice structure makes working current and voltage of the device lowered, resulting in realization of more efficient devices.

Nitride semiconductor device

The deposition of silicon carbide thin films and the associated technologies of impurity incorporation, etching, surface chemistry, and electrical contacts for fabrication of solid-state devices capable of operation at temperatures to 925 K are addressed. The results of several research programs in the United States, Japan and the Soviet Union, and the remaining challenges related to the development of silicon carbide for microelectronics are presented and discussed. It is concluded that the combination of alpha -SiC on alpha -SiC appears especially viable for device fabrication. In addition, considerable progress in the understanding of the surface science, ohmic and Schottky contacts, and dry etching have recently been made. The combination of these advances has allowed continual improvement in Schottky diode p-n junction, MESFET, MOSFET, HBT, and LED devices. >

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Thin film deposition and microelectronic and optoelectronic device fabrication and characterization in monocrystalline alpha and beta silicon carbide

Semiconductor light emitting devices and methods of producing same are provided The semiconductor light emitting devices include a substrate that has a surface including a difference-in-height portion composed of, for example, a wurtzite compound A crystal growth layer is formed in the substrate surface wherein at least a portion of which is oriented along an inclined plane with respect to a principal plane of the substrate The semiconductor device includes a first conductive layer, an active layer and a second conductive layer formed on the crystal layer in a stacked arrangement and oriented along the inclined place

Semiconductor light emitting device and fabrication method thereof

The present disclosure relates to a semiconductor light emitting device, comprising: a plurality of semiconductor layers, including a first semiconductor layer having a first conductivity, a second semiconductor layer having a second conductivity different from the first conductivity, and an active layer interposed between the first semiconductor layer and the second semiconductor layer, generating light via electron-hole recombination; a first electrode, supplying either electrons or holes to the plurality of semiconductor layers; a second electrode, supplying, to the plurality of semiconductor layers, electrons if the holes are supplied by the first electrode, or holes if the electrons are supplied by the first electrode; a non-conductive distributed bragg reflector coupled to the plurality of semiconductor layers, reflecting the light from the active layer; and a first light-transmitting film coupled to the distributed bragg reflector from a side opposite to the plurality of semiconductor layers with respect to the non-conductive distributed bragg reflector, with the first light-transmitting film having a refractive index lower than an effective refractive index of the distributed bragg reflector.

Semiconductor Light Emitting Device

Continuous-wave operation at room-temperature has been demonstrated for InGaN multi-quantum-well (MQW) laser diodes (LDs) grown on low-dislocation-density n-GaN substrates with a backside n-contact. The current, current density and voltage at the lasing threshold were 144 mA, 10.9 kA/cm2 and 10.5 V, respectively, for a 3 µm wide ridge-geometry diode with high-reflection dielectric coated mirrors. Single-transverse-mode emission was observed in the far-field pattern of the LDs and the beam full width at half power in the parallel and perpendicular directions was 6° and 25°, respectively.

https://iopscience.iop.org/article/10.1143/JJAP.38.L184/pdf

Room-Temperature Continuous-Wave Operation of InGaN Multi-Quantum-Well Laser Diodes Grown on an n-GaN Substrate with a Backside n-Contact

Precise control of pn-junction profiles for GaN-based LD structures using GaN substrates with low dislocation densities

Homoepitaxial growth on a 6H-SiC (0001)Si face was carried out successfully at 1500°C by chemical vapor deposition. This temperature is 300°C lower than typical well-known growth temperatures. The p-n junction diodes were fabricated with the grown layers and showed very good rectification. The breakdown electric field was estimated to be 2.4×106 V/cm using the characteristics of the p-n junction diodes. This value is comparable with high-temperature grown layers. The fabricated p-n junction diodes showed blue light emission in the forward-biased region.

https://iopscience.iop.org/article/10.1143/JJAP.26.L1815/pdf

Fabrication of P-N Junction Diodes Using Homoepitaxially Grown 6H-SiC at Low Temperature by Chemical Vapor Deposition

Electron paramagnetic resonance of ${\mathrm{Cu}}^{2+}{(d}^{9})$ has been detected optically in the visible and near-infrared luminescence of wurtzite GaN. Its effective $\mathcal{S}=1/2$ spin Hamiltonian parameters are ${g}_{\ensuremath{\Vert}}=\ifmmode\pm\else\textpm\fi{}0.20(5),$ ${g}_{\ensuremath{\perp}}=+1.549(1),$ and ${|}^{63}{A}_{\ensuremath{\Vert}}|=550(50)$ MHz, and ${|}^{63}{A}_{\ensuremath{\perp}}|=570(5)$ MHz. A crystal field theory of the g values is presented, which identifies the ion as substitutional on the Ga sublattice. Possible mechanisms for its presence in the luminescence are discussed.

Electron paramagnetic resonance of Cu ( d 9 ) in GaN

PROBLEM TO BE SOLVED: To provide a method of epitaxial growing by which very flat surface morphology can be obtained even in a III-V family semiconductor thick film, which is hetero-epitaxially grown on a hybrid substrate with different lattice constant and thermal expansion coefficient. SOLUTION: A selective growth region is set through the use of a mask 13 on a substrate 11 having off-orientation of about 0.3 deg. or more. A group III-V compound semiconductor exhibiting a lattice constant and a thermal expansion coefficient different from those of the substrate 11 is formed with facet construction in the region and the facet construction is grown, while it is embedded with the mask 13 to obtain a group III-V compound semiconductor film exhibiting extremely good planarity. Also, a semiconductor lamination including double-hetero joint is formed on the group III-V compound semiconductor film to obtain a light emitting device exhibiting very few crystal defects and a long device service life.

Naotaka Kuroda

Papers

Room-Temperature Continuous-Wave Operation of InGaN Multi-Quantum-Well Laser Diodes Grown on an n-GaN Substrate with a Backside n-Contact

Precise control of pn-junction profiles for GaN-based LD structures using GaN substrates with low dislocation densities

Fabrication of P-N Junction Diodes Using Homoepitaxially Grown 6H-SiC at Low Temperature by Chemical Vapor Deposition

Electron paramagnetic resonance of Cu ( d 9 ) in GaN

Method for growing group iii-v compound semiconductor and manufacture of semiconductor light emitting device using the method