A novel route to synthesize diphenylene by the catalytic effect of GaP nanocrystals

Diphenylene was synthesized directly from benzene under the catalytic effect of GaP nanocrystals, and the effect of GaP nanocrystals content was studied. The experimental results showed that no reactions took place without GaP nanocrystals. The more the GaP nanocrystals added, the more the reaction complete. Furthermore, at high temperatures (450-480℃), when the content of GaP nanocrystals was high enough, almost all benzene polymerized and the yield of diphenylene was rather high. On the contrast, even if there are enough GaP nanocrystals in the reaction mixture, almost no polymerization reaction took place at low temperature (for example, 250-300℃), and the yield of diphenylene was very poor. The analytical results of XRD, IR, elemental analysis and NMR proved that the sample was truly diphenylene.     

Growth and optical properties of strained (AIP)n (GaP)n short-period superlattices

Biaxial tensile strain is introduced into (AlP)_n(GaP)_n superlattices (SLs) by growing the SLs on slightly lattice-mismatched InGaP intermediate layers on GaP(00l) substrates. A significant enhancement of photoluminescence intensity is observed for the strained (AlP)_n (GaP)_n short-period SLs, especially for those with n≤ 3.     

外部电光测量的空间分辨率

报道了用650nm的半导体激光二极管建立的一个正面入射式外部电光测量装置.用〈100〉面镀红光全反射膜的半绝缘GaP作为外部探头,提出以有效调制电压为测量对象,对外部电光测量装置进行了电场空间分辨率的测量.实验结果表明,电场空间分辨率小于1μm,电压灵敏度为12.6mV/ Hz.     

Accelerated degradation in GaP and GaAsxPl−x(x=0.15∼0.32) visible leds by contaminant Cu during forward bias operation

Reliability for GaP and GaAs_xP_1-x(x=0.15~0.32) visible light-emitting diodes (LEDs) was investigated in regard to their Cu contamination effect. Cu contamination magnified the amount of light output degradation for LEDs with active layers grown by vapor phase epitaxy (VPE), but did not magnify it so much for the case of LEDs with active layers grown by liquid phase epitaxy (LPE). Cu contamination effect on LEDs was revealed to have a correlation with LED material growth procedure, but no correlation with LED material bandgap. A hole trap with 0.80 eV activation energy was observed in the p-type layers of degraded LEDs with Cu contamination and forward bias operation. Contaminant Cu was deduced to move into LED bulk crystals at room temperature, and to be drawn near depletion layers by an electric field, as explained by the Longini model.     

Crystalline to amorphous transformations in ion implanted GaP

Abstract

The amorphization process of GaP by ion implantation is studied. The samples of 〈111〉 oriented GaP were implanted at 130 K with various doses 5 × 10¹³-2 × 10¹⁶ cm^?2 of 150 keV N⁺ ions and with the doses of 6 × 10¹²-1.5 × 10¹⁵ cm^?2 of 150 keV Cd⁺ ions. Room temperature implantations were also performed to see the influence of temperature on defect production. Rutherford backscattering and channelling techniques were used to determine damage in crystals. The damage distributions calculated from the RBS spectra have been compared with the results of Monte-Carlo simulation of the defect creation.

The estimated threshold damage density appeared to be independent on ion mass and is equal 6.5 × 10²⁰ keV/cm³. It is suggested that amorphization of GaP is well explained on the basis of a homogenous model.     

X ray absorption spectroscopy investigation of phase transition in Ge,GaAs and GaP

Abstract

The phase transitions of GaAs, GaP and Ge under pressure have been investigated by x-ray absorption spectroscopy (XAS). At the onset of the transition the Debye-Waller factor increases and the x-ray absorption near edge structure (XANES) is progressively modified. A mixing of the low and high pressure phase can be determined by XAS as well as amorphization of the sample on pressure release.     

磷化镓高功率太赫兹共线差频源的研究

在众多实现太赫兹辐射的方法中, 非线性光学共线差频能够实现高功率、宽波段、连续可调谐的太赫兹波辐射. 理论分析表明, 各向同性磷化镓晶体, 在1064 nm附近波长激光共线差频下具有毫米量级的相干长度, 能够满足高功率宽波段的太赫兹辐射条件.实验证明, 磷化镓晶体共线差频实现高功率宽波段的太赫兹光辐射, 其太赫兹光波长调谐范围为95.9–773.4 μm (0.39–3.13 THz), 最高峰值功率7 W位于频率2.0 THz处.该实验结果与理论计算基本保持一致. 关键词： 太赫兹源 磷化镓 共线差频     

GaP:N绿色LEDn_2层载流子浓度的优化

在已报道的ｐ－ｎ２－ｎ１结的势垒分布计算的基础上，对该结构的浓度分布进行了计算。对于正偏情形，计入了ｎ２区产生的压降。考虑到ＧａＰ：ＮＬＥＤ发光区主要在ｐ区，注入效率γ＝ｊｎ/（ｊｎ＋ｊｐ），ｊｎ和ｊｐ分别为电子电流和空穴电流。ｐ区内的少子扩散可视为向无限远处的一维扩散；ｎ２区内外加正向偏压时电场不能忽略，空穴又被ｎ２－ｎ１结势垒阻挡（设被完全阻挡），则问题归结为求解有限厚度层中空穴的扩散和复合方程，由边界条件求出空穴扩散电流。将求出的电子扩散电流和空穴扩散电流代入注入效率的表达式即可求得γ。对在合理的参数值范围内的计算结果进行了讨论。分析表明：当ｎ２值在１０１５～１０１６ｃｍ－３范围内时，注入效率较高，与实验结果基本相符。     

Quantitative esr analysis of deep defects in LEC-grown GaP

Defects in LEC GaP have been analyzed quantitatively using an ESR method. Transition-metal impurities and native defects were studied in as-grown crystals. The antisite defect, P_Ga, and the isolated gallium vacancy, V_Ga, were emphasized since no other method has given definite, quantitative information on these defects. P_Ga antisites are present in some Cr-doped and some Zn-dopeii samples in concentrations high enough to affect their electrical properties. V_Ga was not detected in as-grown crystals indicating that V_Ga concentrations are smaller than the antisite concentrations at least in p-type material. Typical ESR detection., limits for transition-metal impurities are in the middle 10¹⁴ cm⁻³ range. The method is especially sensitive to Fe traces which were observed in all the samples studied. Work performed while the author was a visiting scientist at TAF Freiburg,     

A Stress‐Free and Textured GaP Template on Silicon for Solar Water Splitting

This work shows that a large‐scale textured GaP template monolithically integrated on Si can be developed by using surface energy engineering, for water‐splitting applications. The stability of (114)A facets is first shown, based on scanning tunneling microscopy images, transmission electron microscopy, and atomic force microscopy. These observations are then discussed in terms of thermodynamics through density functional theory calculations. A stress‐free nanopatterned surface is obtained by molecular beam epitaxy, composed of a regular array of GaP (114)A facets over a 2 in. vicinal Si substrate. The advantages of such textured (114)A GaP/Si template in terms of surface gain, band lineups, and ohmic contacts for water‐splitting applications are finally discussed.