An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

In this review, the structural, mechanical, thermal, and chemical properties of substrates used for gallium nitride (GaN) epitaxy are compiled, and the properties of GaN films deposited on these substrates are reviewed. Among semiconductors, GaN is unique; most of its applications uses thin GaN films deposited on foreign substrates (materials other than GaN); that is, heteroepitaxial thin films. As a consequence of heteroepitaxy, the quality of the GaN films is very dependent on the properties of the substrate—both the inherent properties such as lattice constants and thermal expansion coefficients, and process induced properties such as surface roughness, step height and terrace width, and wetting behavior. The consequences of heteroepitaxy are discussed, including the crystallographic orientation and polarity, surface morphology, and inherent and thermally induced stress in the GaN films. Defects such as threading dislocations, inversion domains, and the unintentional incorporation of impurities into the epitaxial GaN layer resulting from heteroepitaxy are presented along with their effect on device processing and performance. A summary of the structure and lattice constants for many semiconductors, metals, metal nitrides, and oxides used or considered for GaN epitaxy is presented. The properties, synthesis, advantages and disadvantages of the six most commonly employed substrates (sapphire, 6H-SiC, Si, GaAs, LiGaO 2 , and AlN) are presented. Useful substrate properties such as lattice constants, defect densities, elastic moduli, thermal expansion coefficients, thermal conductivities, etching characteristics, and reactivities under deposition conditions are presented. Efforts to reduce the defect densities and to optimize the electrical and optical properties of the GaN epitaxial film by substrate etching, nitridation, and slight misorientation from the (0 0 0 1) crystal plane are reviewed. The requirements, the obstacles, and the results to date to produce zincblende GaN on 3C-SiC/Si(0 0 1) and GaAs are discussed. Tables summarizing measures of the GaN quality such as XRD rocking curve FWHM, photoluminescence peak position and FWHM, and electron mobilities for GaN epitaxial layers produced by MOCVD, MBE, and HVPE for each substrate are given. The initial results using GaN substrates, prepared as bulk crystals and as free-standing epitaxial films, are reviewed. Finally, the promise and the directions of research on new potential substrates, such as compliant and porous substrates are described.

Substrates for gallium nitride epitaxy

A nitride semiconductor light-emitting device has an active layer of a single-quantum well structure or multi-quantum well made of a nitride semiconductor containing indium and gallium. A first p-type clad layer made of a p-type nitride semiconductor containing aluminum and gallium is provided in contact with one surface of the active layer. A second p-type clad layer made of a p-type nitride semiconductor containing aluminum and gallium is provided on the first p-type clad layer. The second p-type clad layer has a larger band gap than that of the first p-type clad layer. An n-type semiconductor layer is provided in contact with the other surface of the active layer.

Nitride semiconductor light emitting device

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 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

Provided is a nitride semiconductor having a larger low-defective region on a surface thereof, a semiconductor device using the nitride semiconductor, a method of manufacturing a nitride semiconductor capable of easily reducing surface defects in a step of forming a layer through lateral growth, and a method of manufacturing a semiconductor device manufactured by the use of the nitride semiconductor. A seed crystal portion is formed into stripes on a substrate with a buffer layer sandwiched therebetween. Then, a crystal is grown from the seed crystal portion in two steps of growth conditions to form a nitride semiconductor layer. In a first step, a low temperature growth portion having a trapezoidal-shaped cross section in a layer thickness direction is formed at a growth temperature of 1030° C., and in a second step, lateral growth predominantly takes place at a growth temperature of 1070° C. Then, a high temperature growth potion is formed between the low temperature growth portions. Thereby, hillocks and lattice defects can be reduced in a region of the surface of the nitride semiconductor layer above the low temperature growth portion.

Nitride semiconductor, semiconductor device, and method of manufacturing the same

To provide a semiconductor device capable of enhancing crystallinity of a semiconductor of a III-V group compound of a nitride system formed on a sapphire substrate and to provide a method of manufacturing the same. On the sapphire substrate, after forming a seed crystal layer having a crystalline part and an opening part made of a crystal of the semiconductor of the III-V group compound of the nitride system, a concave part communicatively connected to the opening part is formed within the substrate. Then, an n-side contact layer is grown from the crystalline part. Since the lateral grown crystal and the sapphire substrate does not contact, in the n-side contact layer and the crystal of the semiconductor of the III-V group compound of the nitride system grown thereon, density of penetration dislocation restricts lower and a crystal orientation less changes.

Semiconductor device and method of manufacturing the same

In a multi-beam semiconductor laser including nitride III-V compound semiconductor layers stacked on one surface of a substrate of sapphire or other material to form laser structures, and including a plurality of anode electrodes and a plurality of cathode electrodes formed on the nitride III-V compound semiconductor layers, one of the anode electrodes is formed to bridge over one of the cathode electrodes via an insulating film, and another anode electrode is formed to bridge over another of the cathode electrodes via an insulating film.

Multibeam semiconductor laser, semiconductor light- emitting device and semiconductor device

The epitaxial lateral overgrowth (ELO) technique is an important technology for improving the characteristics of GaN-based laser diodes (LDs). The photoluminescence intensities from GaN and GaInN multiple quantum well active layers in the ELO-GaN wing region were found to be higher than those in the seed region. This indicates that the density of dislocations in the wing region could be reduced significantly. This is evidenced by dislocation densities of less than 106 cm-2 as determined from transmission emission microscopy and etching-pit-density measurements. The cleaved facets of LDs on ELO-GaN and sapphire were observed by atomic forced microscopy. Although the roughness of GaN cleaved facets on sapphire were high (Ra>10 nm), the roughness in the ELO-GaN wing region was found to be as smooth as that of GaAs cleaved facet (Ra<1 nm). The characteristics of LDs on ELO-GaN were found to be superior to those on sapphire as a result of smoother facets and lower dislocation densities.

https://iopscience.iop.org/article/10.1143/JJAP.40.3206/pdf

GaN-Based High Power Blue-Violet Laser Diodes

In a semiconductor light emitting device such as a semiconductor laser using nitride III-V compound semiconductors and having a structure interposing an active layer between an n-side cladding layer and a p-side cladding layer, the p-side cladding layer is made of an undoped or n-type first layer 9 and a p-type second layer 12 that are deposited sequentially from nearer to remoter from the active layer. The first layer 9 is not thinner than 50 nm. The p-type second layer 12 includes a p-type third layer having a larger band gap inserted therein as an electron blocking layer. Thus the semiconductor light emitting device is reduced in operation voltage while keeping a thickness of the p-side cladding layer necessary for ensuring favorable optical properties.

Motonobu Takeya

Papers

Nitride semiconductor, semiconductor device, and method of manufacturing the same

Semiconductor device and method of manufacturing the same

Multibeam semiconductor laser, semiconductor light- emitting device and semiconductor device

GaN-Based High Power Blue-Violet Laser Diodes

Semiconductor light emitting device and its manufacturing method