稀磁半导体的研究进展

本文主要介绍了III-V族稀磁半导体(Ga,Mn)As的研究进展,包括(Ga,Mn)As的生长制备、基本磁性质、磁输运特征、磁光性质、磁性起源、相关的异质结构和自旋注入等,同时还简单介绍了其它稀磁半导体如IV族、III-VI族和IV-VI族等稀磁半导体的研究进展,在文章的最后描述了理想的稀磁半导体应该具备的特征以及对未来的展望。     

Cr掺杂InAs自组织量子点的分子束外延生长及磁性质

利用低温分子束外延技术制备了Cr掺杂的InAs铁磁性自组织量子点.高分辨电子显微镜分析表明InAs:Cr量子点保持了较好的闪锌矿结构.超导量子干涉仪磁性测量表明InAs:Cr自组织量子点的铁磁转变温度超过400K.     

Effect of Annealing on Structural and Magnetic Properties of a Thick （Ga,Mn）As Layer

We investigate effects of annealing on magnetic properties of a thick (Ga,Mn)As layer, and find a dramatic increase of the Curie temperature from 65 to 115K by postgrowth annealing for a 500-nm (Ga,Mn)As layer.Auger electron spectroscopy measurements suggest that the increase of the Curie temperature is mainly due to diffusion of Mn interstitial to the free surface. The double-crystal x-ray diffraction patterns show that the lattice constant of (Ga,Mn)As decreases with increasing annealing temperature. As a result, the annealing induced reduction of the lattice constant is mainly attributed to removal of Mn interstitial.     

Anomalous Pressure Behavior of N-Cluster Emissions in GaAs0.973Sb0.022N0.005

Photoluminescence of GaAs0.973Sb0.022N0.005 is investigated at different temperatures and pressures. Both the alloy band edge and the N-related emissions, which show different temperature and pressure dependences, are observed. The pressure coefficients obtained in the pressure range 0-1.4GPa for the band edge and N-related emissions are 67 and 45meV/GPa, respectively. The N-related emissions shift to a higher energy in the lower pressure range and then begin to redshift at about 8.5GPa. This redshift is possibly caused by the increase of the X-valley component in the N-related states with increasing pressure.     

低温退火对稀磁半导体(Ga,Mn)As性质的影响

利用低温分子束外延技术在GaAs(001)上外延生长出厚度为500nm的稀磁半导体(Ga,Mn)As薄膜. 双晶X射线衍射证明其为闪锌矿结构，晶格参数为0.5683nm，据此推导出其Mn含量为7%. 磁测量结果揭示其铁磁转变温度为65K. 观察了低温退火处理对(Ga,Mn)As磁性质的影响，发现生长后退火处理显著提高了其铁磁转变温度，可以达到115K.     

稀磁半导体的研究进展

本文主要介绍了III-V族稀磁半导体(Ga,Mn)As的研究进展,包括(Ga,Mn)As的生长制备、基本磁性质、磁输运特征、磁光性质、磁性起源、相关的异质结构和自旋注入等,同时还简单介绍了其它稀磁半导体如IV族、III-VI族和IV-VI族等稀磁半导体的研究进展,在文章的最后描述了理想的稀磁半导体应该具备的特征以及对未来的展望。     

Electro-oxidation of Formic Acid on Carbon Supported Edge-Truncated Cubic Platinum Nanoparticles Catalysts

The oxidation of formic acid on edge-truncated cubic platinum nanoparticles/C catalysts is investigated. X-ray photoelectron spectroscopy analysis indicates that the surface of edge-truncated cubic platinum nanoparticles is composed of two types of coordination sites. ＇/＇he oxidation behavior of formic acid on edge-truncated cubic platinum nanoparticles/C is investigated using cyclic voltammetry. The apparent activation energies are found to be 54.2, 55.0, 61.8, 69.5, 71.9, 69.26, 65.28k J/tool at 0.15, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7V, respectively. A specific surface area activity of 1.76 mA·cm^-2 at 0.4 V indicates that the edge-truncated cubic Platinum nanoparticles are a promising anode catalyst for direct formic acid fuel cells.     

GaMnAs合金中等离子体激元-LO声子耦合模的拉曼光谱研究

理论分析了两种阻尼条件下重掺杂GaAs中的等离子体激元-LO声子耦合模,证实在小阻尼条件下耦合模的拉曼谱分为两支,而在大阻尼条件下只有一个耦合模可以被观测到。推导得到了只出现一个耦合模所需的最小阻尼的解析表达式。测量了Mn组分从2.6%到9%的GaMnAs合金的拉曼光谱。利用等离子体激元-LO声子耦合模理论进行了谱形拟合,得到了所测的GaMnAs合金中的空穴浓度。     

Cr掺杂InAs自组织量子点的分子束外延生长及磁性质

利用低温分子束外延技术制备了Cr掺杂的InAs铁磁性自组织量子点.高分辨电子显微镜分析表明InAsCr量子点保持了较好的闪锌矿结构.超导量子干涉仪磁性测量表明InAsCr自组织量子点的铁磁转变温度超过400K.     

真空镀膜技术的应用及教学实验

 真空镀膜技术广泛应用于现代科学技术的很多领域。起初最主要用于光学薄膜。最典型的方法是采用真空蒸发法将成膜材料按设计要求淀积在工件表面从而获得所需的反射、增透、截止、带通、偏振等效果。