Growth of direct bandgap GalnP quantum dots on GaP substrates

GaInP has a direct bandgap for In concentrations higher than approximately 30%, and the band-lineup between GaInP and GaP is type-II for In concentrations less than 60%. Therefore, in order to use GaInP as the active light-emitting layer in an optoelectronic device grown on GaP, the strain induced by the lattice mismatch between GaInP and GaP has to be somehow managed such that formation of crystal defects is suppressed. One method is to grow the layer thinner than the critical thickness. Another method that recently received much attention is to grow strain-induced Stranski-Krastanov islands (sometimes referred to as self-assembled quantum dots). Small droplets of highly latticmismatched materials have been embedded into single crystals without generating defects such as threading dislocations and stacking faults using this method. We have grown a series of GaInP/GaP layers by metalorganic chemical vapor deposition and have studied the light emission from them. Ordered GaInP islands were found to be responsible for the light emission. We present the light emission characteristics of these ordered GaInP/GaP islands, and their dependence on various growth parameters.     

Thin layers of GaInP, GaP and GaAsP in metalorganic vapour phase epitaxy-grown resonant tunnelling diodes

We have studied the epitaxial growth and electrical performance of Al-free, GaAs-based, resonant tunnelling diodes (RTDs) including thin barriers of GaInP, GaP, or GaAs_xP_1−x. n-Type tunnelling diodes have been fabricated and the symmetry in the current–voltage (I–V) characteristics, as well as the peak-to-valley ratios, are found to be sensitive probes for the interface quality in the heterostructures. For GaInP RTDs, we show that the introduction of GaP intermediate layers is crucial for the realisation of a useful tunnelling current. RTDs including thin barriers (less than about 10 monolayers (ML)) of GaP are realised, but the strong mismatch between the materials limit the useful thickness. Finally, RTDs with GaAs_xP_1−x alloys are fabricated showing the best peak-to-valley ratio of the diodes (about 5), as well as a symmetric I–V characteristics. The electrical data are further compared to studies by transmission electron microscopy (TEM) in the various material systems.     

Realization of p-ZnO thin films by GaP codoping

An attempt has been made to realize p-ZnO by directly doping (codoping) GaP into ZnO thin films. GaP codoped ZnO thin films of different concentrations (1, 2 and 4 mol%) have been grown by RF magnetron sputtering. The grown films on sapphire substrate have been characterized by X-ray diffraction (XRD), Hall measurement, Photoluminescence (PL) and Energy dispersive spectroscopy (EDS) to validate the p-type conduction. XRD result shows that all the films have been preferentially oriented along (0 0 2) orientation. The decrease of full-width at half maximum (FWHM) with increase in GaP doping depicts the decrease in native donor defects. Hall measurement shows that among the three films, 2 and 4 mol% GaP doped ZnO shows p-conductivity due to the sufficient amount of phosphorous incorporation. It has been found that low resistivity (2.17 Ωcm) and high hole concentration (1.8×10¹⁸ cm⁻³) for 2% GaP codoped ZnO films due to best codoping. The red shift in near-band-edge (NBE) emission and donar-acceptor-pair (DAP) and neutral acceptor bound recombination (A°X) observed by room temperature and low temperature (10 K) PL, respectively, well acknowledged the formation of p-ZnO. The incorporated phosphorous in the film has been also confirmed by EDS analysis.     

Electrical characterization of thiols self-assembled layers on GaP (1 1 1) structures

The experimental studies on III–V semiconductor compounds surface passivation phenomena are mainly dedicated to solve some technological problems as those regarding the ways to keep the chemical stability of native oxides on surfaces. Self-assembled monolayers (SAMs) provide a simple way to produce relatively ordered structures at a molecular scale, which seems to be capable to protect the clean surface against the evolution of oxidation process. In this respect, thin films of SAMs of aliphatic thiol (dodencanthiol—CH₃(CH₂)₁₁SH) and aromatic thiol (4, 4′ tiobisbenzenthiol-S (C₆H₄SH)₂ have been deposited on the surface of GaP (1 1 1) samples. The electrical properties measurements of some structures based on GaP compound was performed. There were recorded current–voltage (I–V) characteristics for complex structures AuGeNi/R-SH/GaP and AuGeNi/Ar-SH/GaP in darkness and also exposed to a Xe lamp. In dark and in “reverse bias” way, the I–V characteristics present the feature of a Zenner diode for GaP/Ar-SH and a gradual increase of current for GaP/R-SH. In dark and “in forward bias” way, the current increases as for a normal diode for both GaP/Ar-SH and GaP/R-SH structures. The complex structures (e.g.: In/AuGeNi/R-SH/GaP/R-SH/AuGeNi/In) are less sensitive to light. The SEM analysis performed on a GaP/R-SH surface shows a continuous packed up layer while GaP/Ar-SH looks like an inhomogeneous deposition of layers with different thickness regions. The diodes’ ideality factors determined from I–V characteristics are unusually high (n2) as a possible result of inhomogeneous Schottky contacts or due to ageing effects, in the field of degradation.     

质子轰击GaP电光采样测量

在ｎ－ＧａＰ衬底上制作共面波导（ＣＰＷ）,用质子轰击的方法减小共面波导的漏电损失,用倍频扫描移相电光采样技术测量了１～５ＧＨｚ微波信号．质子轰击后ＧａＰＣＰＷ的电阻增大了４个量级,在２．３０ＧＨｚ微波信号时,质子轰击ＧａＰＣＰＷ电光采样测量获得了１０ｍＶ／Ｈｚ的电压灵敏度．     

用SiH_4-N_2进行PECVD生长高质量SiN研究

用ＳｉＨ４┐Ｎ２进行ＰＥＣＶＤ生长高质量ＳｉＮ研究刘英坤李明月（电子工业部第十三研究所，石家庄，０５００５１）１引言众所周知，氮化硅薄膜，尤其是低温等离子体淀积的氮化硅薄膜ＰＥＣＶＤ—ＳｉｘＮｙ，因其良好的物理化学性质和优越的制备工艺，在现代半导体器...     

InP/GaP晶格失配界面的电特性

本文研究了InP/GaP晶格失配界面的电特性。HRTEM图象表明在界面存在90°位错缺陷的应变缓释。ECV表明界面存在高密度载流子层。AFM图象表明本研究中获得了粗糙度为2.48nm的良好InP异质外延层。并对于InP界面给出了一个基于费米能级钉扎的模型来解释观察到的电性质。     

基于Mie散射理论的光子晶体安德森定域化研究

基于Mie散射理论和低浓度近似,对磷化镓光子晶体的安德森定域化进行了理论计算,并分析了影响定域化参量的各种因素。结果表明,在浓度为10%,折射率比值大于3.8,无吸收状态下,中红外区出现了安德森定域化现象,并且随粒子半径的增大,定域化区向长波段移动,且基质折射率的增大使定域化现象减弱。研究结果为该类晶体的定域化现象提供了理论参考。     

GaP低阻欧姆接触层的AES和SIMS分析

本文用AES和SIMS分析讨论了p-GaP与三层金属膜Pd/Zn/Pd形成良好欧姆接触层的性质.     

Raman Spectra of AlP／GaP Short—period Superlattice

The samples of (AlP)n/(GaP)n short-period superlattics(period number n=4,6)grown by MOVPE and the sample of n-GaP(100)single crystal substrate are measured and analyzed by Raman spectrum.In the three kinds of samples,the double-phonon modes of first-order Raman scattering peaks are all existent.Moreover,the second-order Raman scattering peaks are observed to exist.