AlInN/GaN heterostructures with indium contents between 20% and 35% were grown by metal organic vapour phase epitaxy on high purity silicon (1 1 1) substrates. The samples were investigated by photovoltage (PV) spectroscopy whereby the individual layers were distinguished by their different absorption edges. The near band-edge transitions of GaN and of Si demonstrate the existence of space charge regions within the GaN layers and the Si substrate. In sandwich geometry the Si substrate significantly influences the PV spectra which are strongly quenched by additional 690 nm laser light illumination. The intensity dependence and the saturation behaviour of quenching suggest a recharging of Si- and GaN-related interface defects causing a collapse of the corresponding PV signals in the space charge region. From additional scanning surface potential microscopy measurements in bevel configuration further evidence of the existence of different space charge regions at the GaN/AlN/Si and AlInN/GaN interfaces is obtained. The properties of the Si/seed layer/GaN heterostructure are discussed in terms of a p-type Si/n-type GaN layer interface generated by diffusion of Si atoms into GaN and of Ga or Al atoms into the Si substrate. Source:IOPscience For more information, please visit our website: www.semiconductorwafers.net, send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com
The superconducting X-ray detector developed by AIST, used to identify N dopants at a very low concentration in SiC (left) and SC-XAFS installed at a beam line of Photon Factory, KEK (right) AIST researchers have developed an instrument for X-ray absorption fine structure (XAFS) spectroscopy equipped with a superconducting detector. With the instrument, the researchers have realized, for the first time, local structure analysis of nitrogen (N) dopants (impurity atoms at a very low concentration), which were introduced by ion plantation in silicon carbide (SiC), a wide-gap semiconductor, and are necessary for SiC to be a n-type semiconductor. Wide-gap semiconductor power devices, which enable reduction of power loss, are expected to contribute to the suppression of CO2 emissions. To produce devices using SiC, one of the typical wide-gap semiconductor materials, introduction of dopants by ion plantation is necessary for the control of electrical properties. The dopant atoms need to be located in the particular lattice site in a crystal. However, there has not been a microstructure analysis method. SC-XAFS was used to measure the XAFS spectra of the N dopants at a very low concentration in the SiC crystal, and the substitution site of the N dopants was determined by comparison with a first-principle calculation. In addition to SiC, SC-XAFS can be applied to wide-gap semiconductors such as gallium nitride (GaN) and diamond, magnets for low-loss motors, spintronics devices, solar cells, etc. The results will be published online in Scientific Reports, a scientific journal published by the Nature Publishing Group, on November 14, 2012 (UK time). SiC has a band gap larger than that of general semiconductors and possesses excellent properties including chemical stability, hardness, and heat resistance. Therefore, it is expected to be a next-generation energy-saving semiconductor which can function in a high-temperature environment. In recent years, large single-crystal SiC substrates have become available and devices such as diodes and transistors appeared on the market; however, doping, which is necessary to produce devices with the semiconductor, is still imperfect, preventing SiC from fully utilizing its intrinsic energy-saving properties. characteristic X-ray of oxygen (b) An example of the detection of the N dopant in a very low concentration in SiC The strong peak of abundant C in SiC and the weak peak of N are distinguishable. In the insertion in (b), the vertical axis is in a linear scale. It is clear that N exists in a very low concentration. Doping is a process in which a small amount of impurity is introduced (for substitution) into a crystal lattice site to form a semiconductor with electrons playing a major role in electrical conduction (n-type semiconductor) or with holes playing a major role in electrical conduction (p-type semiconductor). SiC is a compound, and thus has a complex crystal structure, which means that doping into SiC is by fa...
We report our results on InGaNAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) in the 1.3 µm range. The epitaxial structures were grown on (1 0 0) GaAs substrates by metalorganic chemical vapour deposition (MOCVD) or molecular beam epitaxy (MBE). The nitrogen composition of the InGa(N)As/GaAs quantum-well (QW) active region is 0–0.02. The long-wavelength (up to 1.3 µm) room-temperature continuous-wave (RT CW) lasing operation was achieved for MBE- and MOCVD-grown VCSELs. For MOCVD-grown devices with n- and p-doped distributed Bragg reflectors (DBRs), a maximum optical output power of 0.74 mW was measured for In0.36Ga0.64N0.006As0.994/GaAs VCSELs. A very low Jth of 2.55 kA cm−2 was obtained for the InGaNAs/GaAs VCSELs. The MBE-grown devices were made with an intracavity structure. Top-emitting multi-mode 1.3 µm In0.35Ga0.65N0.02As0.98/GaAs VCSELs with 1 mW output power have been achieved under RT CW operation. A Jth of 1.52 kA cm−2 has been obtained for the MBE-grown In0.35Ga0.65N0.02As0.98/GaAs VCSELs, which is the lowest threshold current density reported. The emission characteristics of the InGaNAs/GaAs VCSELs were measured and analysed. Source:IOPscience For more information, please visit our website: www.semiconductorwafers.net, send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com
We discovered a new silicon nitride with cubic symmetry formed in the silicon at the Ta/Si interface of the TaN/Ta/Si(100) thin film system when the silicon wafer was annealed at 500 or 600°C. The cubic silicon nitride grew into the silicon crystal in the shape of an inverse pyramid after the annealing process. The boundary planes of the inverse pyramid were the {111} planes of the silicon crystal. The orientation relationship between the silicon nitride and silicon crystal is cubic to cubic. The lattice constant of the new silicon nitride is a=0.5548 nm and is about 2.2% larger than that of the silicon crystal. Source:IOPscience For more information, please visit our website: www.semiconductorwafers.net, send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com
Credit: ESA, CC BY-SA 3.0 IGO A strong but lightweight mirror for space, made from silicon carbide ceramic, is being subjected to the temperature levels and vacuum encountered in orbit. The 95 cm-diameter mirror consists of three separate petals fused together ahead of grinding and polishing. The aim of the test, led for ESA by AMOS in Belgium, was to check if the combination of joints would induce optical distortion when the mirror's temperature was brought close to –150°C. A compound of silicon and carbon, SiC was first synthesised in 1893 in an attempt to make artificial diamonds. The result was not so far off: today, SiC is one of the hardest-known materials, used to make cutting tools, high-performance brakes and even bulletproof vests. Crystalline in nature, it is also used for jewellery. Small amounts of SiC have been unearthed inside meteorites – it is relatively common in deep space. Its strong, lightweight nature made it a natural for human-made space projects too. ESA produced the largest SiC mirror ever to fly in space for the Herschel telescope, launched in 2009. At 3.5 m in diameter, this reflector had twice the observing area of the Hubble Space Telescope while having one third of its mass. Once mastered by ESA, SiC technology has since been used to manufacture a wide variety of space mirrors and optical supports, for missions such as Gaia, Sentinel-2 and the James Webb Space Telescope. Source:phys.org For more information, please visit our website: www.semiconductorwafers.net, send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com.
Xiamen Powerway Advanced Material Co.,Ltd., a leading supplier of GaAs epi wafer and other related products and services announced the new availability of size 2”&4” is on mass production in 2010. This new product represents a natural addition to PAM-XIAMEN's product line. Dr. Shaka, said, "We are pleased to offer GaAs LED epi wafer to our customers including many who are developing better and more reliable for Red Led. It includes algainp led structure with multi quantum well,including DBR layer for LED chip industry, wavelength range from 620nm to 780nm by MOCVD. Therein, AlGaInP is used in manufacture of light-emitting diodes of high-brightness red, orange, green, and yellow color, to form the heterostructure emitting light. It is also used to make diode lasers.The availability improve boule growth and wafering processes." and "Our customers can now benefit from the increased device yield expected when developing advanced transistors on a square substrate. Our led epitaxy are natural by products of our ongoing efforts, currently we are devoted to continuously develop more reliable products." PAM-XIAMEN's improved algainp led structure product line has benefited from strong tech. support from Native University and Laboratory Center. Now we show you specification as follows: p-GaP p-AlGaInP MQW-AlGaInP n-AlGaInP DBR n-ALGaAs/AlAs Buffer GaAs substrate About Xiamen Powerway Advanced Material Co., Ltd Found in 1990, Xiamen Powerway Advanced Material Co., Ltd (PAM-XIAMEN) is a leading manufacturer of compound semiconductor material in China. PAM-XIAMEN develops advanced crystal growth and epitaxy technologies, manufacturing processes, engineered substrates and semiconductor devices. PAM-XIAMEN's technologies enable higher performance and lower cost manufacturing of semiconductor wafer. About GaAs Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells and optical windows. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors including indium gallium arsenide, aluminum gallium arsenide and others. Some electronic properties of gallium arsenide are superior to those of silicon. It has a higher saturated electron velocity and higher electron mobility, allowing gallium arsenide transistors to function at frequencies in excess of 250 GHz. GaAs devices are relatively insensitive to overheating, owing to their wider energy bandgap, and they also tend to create less noise (disturbance in an electrical signal) in electronic circuits than silicon devices, especially at high frequencies. This is a result of higher carrier mobilities and lower resistive device parasitics. These superior properties are compelling reasons to use GaAs circuitry in mobile phones, satellite communications, microwave point-to-point links and higher frequency radar systems. It is...
Schematic of a 10-pair Si-doped AlInN/GaN DBR structure for vertical current injection and (b) a Si-doping profile in a pair of AlInN/GaN layers. Credit: Japan Society of Applied Physics (JSAP) Researchers at Meijo University and Nagoya University in Japan demonstrated a design of GaN-based vertical-cavity surface-emitting lasers (VCSELs) that provides good electrical conductivity and is readily grown. The findings are reported in Applied Physics Express. This research is featured in the November 2016 issue of the online JSAP Bulletin. "GaN-based vertical-cavity surface-emitting lasers (VCSELs) are expected to be adopted in various applications, such as retinal scanning displays, adaptive headlights, and high-speed visible-light communication systems," explain Tetsuya Takeuchi and colleagues at Meijo University and Nagoya University in Japan in their latest report. However, so far, the structures designed for commercialising these devices have poor conducting properties, and existing approaches to improve the conductivity introduce fabrication complexities while performance is inhibited. A report by Takeuchi and colleagues has now demonstrated a design that provides good conduction and is readily grown. VCSELs generally use structures called distributed Bragg reflectors to provide the necessary reflectivity for an effective cavity that allows the device to lase. These reflectors are alternating layers of materials with different refractive indices, which result in a very high reflectivity. Intracavity contacts can help improve the poor conductivity of GaN VCSELs, but these increase the cavity size leading to poor optical confinement, complex fabrication processes, high threshold current densities and a low output-versus-input power efficiency (i.e. the slope efficiency). The low conductivity in DBR structures is the result of polarization charges between the layers of different materials – AlInN and GaN. To overcome the effects of polarization charges, Takeuchi and colleagues used silicon-doped nitrides and introduced "modulation doping" into the layers of the structure. The increased silicon dopant concentrations at the interfaces help to neutralize the polarization effects. Meijo and Nagoya University researchers have also devised a method to expedite the AlInN growth rate to over 0.5 μm/h. The result is a 1.5λ-cavity GaN-based VCSEL with an n-type conducting AlInN/GaN distributed Bragg reflector that has a peak reflectivity of over 99.9% , threshold current of 2.6 mA, corresponding to a threshold current density of 5.2 kA/cm2, and an operating voltage was 4.7V. Source:phys.org For more information, please visit our website: www.semiconductorwafers.net, send us email at angel.ye@powerwaywafer.com or powerwaymaterial@gmail.com
Xiamen Powerway Advanced Material Co.,Ltd., a leading supplier of High Purity Semi-Insulating SiC substrate and other related products and services announced the new availability of size 2”&3”&4” is on mass production in 2017. This new product represents a natural addition to PAM-XIAMEN's product line. Dr. Shaka, said, "We are pleased to offer High Purity Semi-Insulating SiC substrate to our customers. 4H Semi-Insulating Silicon Carbide (SiC) substrates that are available in on-axis orientation. The unique HTCVD crystal growth technology is the key enabler to purer products combining high and uniform resistivity with a very low defect density. The availability improve boule growth and wafering processes." and "Our customers can now benefit from the increased device yield expected when developing advanced transistors on a square substrate. Our High Purity Semi-Insulating SiC substrate are natural by products of our ongoing efforts, currently we are devoted to continuously develop more reliable products." We offer High-purity, semi-insulating (HPSI) 4H-SiC crystals with diameters up to 100 mm, which is grown by the seeded sublimation technology without the intentional deep-level element, such as vanadium dopants. And wafers cut from these crystals exhibit homogeneous activation energies near mid gap and thermally stable semi-insulating (SI) behavior (>10^7 ohm-cm) throughout device processing. Secondary ion mass spectroscopy, deep-level transient spectroscopy, optical admittance spectroscopy, and electron paramagnetic resonance data suggest that the SI behavior originates from several deep levels associated with intrinsic point defects. Micropipe densities in HPSI substrates have been demonstrated to be as low as average typical value 0.8 cm−2 in three inch diameter substrates with TTV=1.7um (median value),WARP=7.7um(median value),and BOW=-4.5um(median value). PAM-XIAMEN's improved High Purity Semi-Insulating SiC substrate product line has benefited from strong tech, support from Native University and Laboratory Center. Now we show you specification as follows: HPSI, 4H SEMI-INSULATING SIC, 2″WAFER SPECIFICATION SUBSTRATE PROPERTY S4H-51-SI-PWAM-250 S4H-51-SI-PWAM-330 S4H-51-SI-PWAM-430 Description A/B Production Grade C/D Research Grade D Dummy Grade 4H SEMI Substrate Polytype 4H Diameter (50.8 ± 0.38) mm Thickness (250 ± 25) μm Resistivity (RT) >1E5 Ω·cm Surface Roughness < 0.5 nm (Si-face CMP Epi-ready); <1 nm (C- face Optical polish) FWHM A<30 arcsec B/C/D <50 arcsec Micropipe Density A+≤1cm-2 A≤10cm-2 B≤30cm-2 C≤50cm-2 D≤100cm-2 Surface Orientation On axis± 0.5° Off axis 3.5° toward± 0.5° Primary flat orientation Parallel {1-100} ± 5° Primary flat length 16.00 ± 1.70 mm Secondary flat orie...
Contact Information
luna@powerwaywafer.compowerwaymaterial@gmail.com 
+86-592-5601 404
