In the past several years, research in each of the wide‐band‐gap semiconductors, SiC, GaN, and ZnSe, has led to major advances which now make them viable for device applications. The merits of each contender for high‐temperature electronics and short‐wavelength optical applications are compared. The outstanding thermal and chemical stability of SiC and GaN should enable them to operate at high temperatures and in hostile environments, and also make them attractive for high‐power operation. The present advanced stage of development of SiC substrates and metal‐oxide‐semiconductor technology makes SiC the leading contender for high‐temperature and high‐power applications if ohmic contacts and interface‐state densities can be further improved. GaN, despite fundamentally superior electronic properties and better ohmic contact resistances, must overcome the lack of an ideal substrate material and a relatively advanced SiC infrastructure in order to compete in electronics applications. Prototype transistors have been fabricated from both SiC and GaN, and the microwave characteristics and high‐temperature performance of SiC transistors have been studied. For optical emitters and detectors, ZnSe, SiC, and GaN all have demonstrated operation in the green, blue, or ultraviolet (UV) spectra. Blue SiC light‐emitting diodes (LEDs) have been on the market for several years, joined recently by UV and blue GaN‐based LEDs. These products should find wide use in full color display and other technologies. Promising prototype UV photodetectors have been fabricated from both SiC and GaN. In laser development, ZnSe leads the way with more sophisticated designs having further improved performance being rapidly demonstrated. If the low damage threshold of ZnSe continues to limit practical laser applications, GaN appears poised to become the semiconductor of choice for short‐wavelength lasers in optical memory and other applications. For further development of these materials to be realized, doping densities (especially p type) and ohmic contact technologies have to be improved. Economies of scale need to be realized through the development of larger SiC substrates. Improved substrate materials, ideally GaN itself, need to be aggressively pursued to further develop the GaN‐based material system and enable the fabrication of lasers. ZnSe material quality is already outstanding and now researchers must focus their attention on addressing the short lifetimes of ZnSe‐based lasers to determine whether the material is sufficiently durable for practical laser applications. The problems related to these three wide‐band‐gap semiconductor systems have moved away from materials science toward the device arena, where their technological development can rapidly be brought to maturity.

Large‐band‐gap SiC, III‐V nitride, and II‐VI ZnSe‐based semiconductor device technologies

We propose a widegap II–VI semiconductor alloy, MgxZn1−xO, for the fabrication of heteroepitaxial ultraviolet light emitting devices based on ZnO. The c-axis oriented MgxZn1−xO films were epitaxially grown by pulsed laser deposition on ZnO epitaxial films and sapphire (0001) substrates using ceramic targets. Solid solution films were prepared with Mg content up to x=0.33, achieving a band gap of 3.99 eV at room temperature. MgO impurity phase segregated at x⩾0.36. Lattice constants of MgxZn1−xO films changed slightly (∼1%), increasing in a axis and decreasing in c-axis direction with increasing x. These films showed ultraviolet photoluminescence at energies from 3.36 (x=0) to 3.87 eV (x=0.33) at 4.2 K.

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MgxZn1−xO as a II–VI widegap semiconductor alloy

The present invention provides a heterocyclic compound and an organic light-emitting device including the heterocyclic compound. The organic light-emitting devices using the heterocyclic compounds have high-efficiency, low driving voltage, high luminance and long lifespan.

Organic light-emitting device

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

Provided is a light emitting diode (LED) manufactured by using a wafer bonding method and a method of manufacturing a LED by using a wafer bonding method. The wafer bonding method may include interposing a stress relaxation layer (33) formed of a metal between a semiconductor layer (20) and a bonding substrate (31). When the stress relaxation layer is used, stress between the bonding substrate and a growth substrate may be offset due to the flexibility of metal, and accordingly, bending or warpage of the bonding substrate may be reduced or prevented.

Light-emitting device and method of manufacturing the same

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

At the time of selective growth of an active layer on a substrate, crystal is previously grown in an active layer non-growth region, and the active layer is grown in an active layer selective growth region. With this configuration, a source supplied to the non-growth region is incorporated in the deposited crystal from the initial stage of growth, so that the supplied amount of the source to the active layer selective growth region is kept nearly at a constant value over the entire period of growth of the active layer, to eliminate degradation of characteristics of the device due to a variation in growth rate of the active layer. In particular, the selective growth method is effective in fabrication of a semiconductor light emitting device including a cladding layer, a guide layer, and an active layer, each of which is formed by selective growth, wherein the active layer has multiple quantum wells.

Selective growth method, and semiconductor light emitting device and fabrication method thereof

A nitride semiconductor element excellent in characteristics even its element structure is three-dimensionally formed by a selective growth or the like, and a production method therefor. A nitride semiconductor element having an electrode layer (21) formed via a high-resistance region such as an undoped gallium nitride layer (17) on the upper layer of a crystal layer having a side surface (16s) and the upper layer (16t) and being grown three-dimensionally. A high resistance region provided to the upper layer (16t) allows current to flow so as to bypass the high resistance region of the upper layer (16t) to form a current route mainly consisting of the side surface (16s) with the upper layer (16t) bypassed. As a result, current is prevented from flowing to the upper layer (16t) having a poor crystallinity.

Nitride semiconductor element and production method for nitride semiconductor element

A semiconductor light-emitting element is provided which has a structure that does not complicate a fabrication process, can be formed in high precision and does not invite any degradation of crystallinity. A light-emitting element is formed, which includes a selective crystal growth layer formed by selectively growing a compound semiconductor of a Wurtzite type, a clad layer of a first conduction type, an active layer and a clad layer of a second conduction type, which are formed on the selective crystal growth layer wherein the active layer is formed so that the active layer extends in parallel to different crystal planes, the active layer is larger in size than a diffusion length of a constituent atom of a mixed crystal, or the active layer has a difference in at least one of a composition and a thickness thereof, thereby forming the active layer having a number of light-emitting wavelength regions whose emission wavelengths differ from one another. The element is so arranged that an electric current or currents are chargeable into the number of light-emitting wavelength regions. Because of the structure based on the selective growth, the band gap energy varies within the same active layer, thereby forming an element or device in high precision without complicating a fabrication process.

Semiconductor light-emitting device and semiconductor light-emitting device

Continuous-wave operation in wide-gap II-VI semiconductor current injection laser diodes at room temperature has been demonstrated for the first time. Stimulated emission was observed at a wavelength of 523.5 nm with a threshold current of 45 mA (1.4 kA/cm2) from ZnCdSe/ZnSe/ZnMgSSe single-quantum-well (SQW) separate-confinement heterostructure (SCH) laser diodes.

Hiroyuki Okuyama

Papers

Semiconductor light emitting device and fabrication method thereof

Selective growth method, and semiconductor light emitting device and fabrication method thereof

Nitride semiconductor element and production method for nitride semiconductor element

Semiconductor light-emitting device and semiconductor light-emitting device

Room temperature continuous operation of blue-green laser diodes