GaNAs基超晶格太阳电池的分子束外延生长与器件特性

采用分子束外延(MBE)生长技术生长了周期厚度不同的1 e V吸收带边的Ga N0.03As0.97/In0.09Ga0.91As应变补偿短周期超晶格(SPSL)。高分辨率X射线衍射(HRXRD)测量结果显示,当周期厚度从6 nm增加到20 nm时,超晶格的结晶质量明显改善。然而,当周期厚度继续增加时,超晶格品质劣化。对超晶格周期良好的样品通过退火优化,获得了具有低温光致发光现象的高含N量Ga NAs/In Ga As超晶格,吸收带边位于1 e V附近。使用10个周期的Ga NAs/In Ga As超晶格(10 nm/10 nm)和Ga As组成的p-i-n太阳电池的短路电流达到10.23 m A/cm2。经聚光测试获得的饱和电流密度、二极管理想因子与由电池暗态电流-电压曲线得到的结果一致。     

V_3X系d带相对移动量的配位场方法的计算

本文用配位场方法计算在D_(2d)晶场作用下,V_3X(X=Si,Ga,Ge,Sb,Sn)超导化合物中d电子各态的附加势能,给出A-15超导化合物d带相对移动模型中的特征量——d子带相对移动量△E_⊥——与晶格常数的解析关系及其数值结果。并用于磁化率的计算。     

Heterogeneous integration of GaAs pHEMT and Si CMOS on the same chip

In this work,we demonstrate the technology of wafer-scale transistor-level heterogeneous integration of Ga As pseudomorphic high electron mobility transistors(p HEMTs) and Si complementary metal–oxide semiconductor(CMOS) on the same Silicon substrate.Ga As p HEMTs are vertical stacked at the top of the Si CMOS wafer using a wafer bonding technique,and the best alignment accuracy of 5 μm is obtained.As a circuit example,a wide band Ga As digital controlled switch is fabricated,which features the technologies of a digital control circuit in Si CMOS and a switch circuit in Ga As p HEMT,15% smaller than the area of normal Ga As and Si CMOS circuits.     

Nanoscale spatial phase modulation of GaAs growth in V-grooved trenches on Si(001) substrate

This letter reports the nanoscale spatial phase modulation of Ga As growth in V-grooved trenches fabricated on a Si(001) substrate by metal–organic vapor-phase epitaxy. Two hexagonal Ga As regions with high density of stacking faults parallel to Si {111} surfaces are observed. A strain-relieved and defect-free cubic phase Ga As was achieved above these highly defective regions. High-resolution transmission electron microscopy and fast Fourier transforms analysis were performed to characterize these regions of Ga As/Si interface. We also discussed the strain relaxation mechanism and phase structure modulation of Ga As selectively grown on this artificially manipulated surface.     

V3X系d带相对移动量的配位场方法的计算

本文用配位场方法计算在D₂d)晶场作用下,V₃X(X=Si,Ga,Ge,Sb,Sn)超导化合物中d电子各态的附加势能,给出A-15超导化合物d带相对移动模型中的特征量——d子带相对移动量△E_⊥——与晶格常数的解析关系及其数值结果。并用于磁化率的计算。 关键词：     

Growth of high-crystallinity uniform GaAs nanowire arrays by molecular beam epitaxy

The self-catalyzed growth of Ga As nanowires(NWs) on silicon(Si) is an effective way to achieve integration between group III–V elements and Si. High-crystallinity uniform Ga As NW arrays were grown by solid-source molecular beam epitaxy(MBE). In this paper, we describe systematic experiments which indicate that the substrate treatment is crucial to the highly crystalline and uniform growth of one-dimensional nanomaterials. The influence of natural oxidation time on the crystallinity and uniformity of Ga As NW arrays was investigated and is discussed in detail. The Ga As NW crystallinity and uniformity are maximized after 20 days of natural oxidation time. This work provides a new solution for producing high-crystallinity uniform III–V nanowire arrays on wafer-scale Si substrates. The highly crystalline uniform NW arrays are expected to be useful for NW-based optical interconnects and Si platform optoelectronic devices.     

Ge_xSi_1-x_/Si应变层超晶格的分子束外延生长及其特性研究

在 Si (l00) 衬底上用分子束外延在不同的温度下生长了不同组份的GeGe_xSi_1-x_/Si 应变层超晶格.用反射式高能电子衍射、x 射线双晶衍射、卢瑟福背散射、透射电子显微镜以及Raman散射等侧试方法研究了Ge Ge_xSi_1-x_/Si超晶格的生长及其结构特性. 结果表明, 对不同合金组份的超晶格, 其最佳生长温度不同. x值小, 生长温度高; 反之, 则要求生长温度低. 对于x为0. 1-0. 6 , 在400-600℃ 的生长温度范围能够长成界面平整、晶格完好和周期均匀的GeGe_xSi_1-x_/Si应变层超晶格. 关键词：     

利用In0.82Ga0.18As与InP衬底之间的应力制作结构材料的缓冲层

采用低压金属有机化学气相淀积(LP-MOCVD)技术,在InP(100)衬底上生长In0.82Ga0.18As,研究生长温度对In0.82Ga0.18As材料表面形貌、结晶质量和电学性能的影响.利用InP(100)衬底与In0.82Ga0.18As材料晶格失配所产生的应变,在不同的生长温度下应变释放程度不同,进而在In...     

稀磁半导体(Ga1-xFex)As的电子结构,磁性及其稳定性的第一性原理研究

采用基于第一性原理的紧束缚近似线性muffin-tin轨道(TB-LMTO-ASA)的方法,在原子球近似的基础上计算了均匀掺杂的稀磁半导体(Ga1-xFex)As在各掺杂浓度下(x=1,1/2,1/4和1/8)的总能量,由能量最低原理得到其在各稳定点的晶格常数,磁性及相应态密度.计算结果表明了(Ga1-xFex)As的晶格常数随掺杂浓度的增大而减小,在各掺杂浓度下(除x=1)样品都是反铁磁态的,Fe 3d和As 4p之间杂化是引起样品电子结构和磁性变化的主要原因.     

不同周期结构硅锗超晶格导热性能研究

构造了均匀、梯度、随机3种不同周期分布的硅/锗(Si/Ge)超晶格结构.采用非平衡分子动力学(NEMD)方法模拟了硅/锗超晶格在3种不同周期分布下的热导率,并研究了样本总长度和温度对热导率的影响.模拟结果表明:梯度和随机周期Si/Ge超晶格的热导率明显低于均匀周期结构超晶格;在不同的周期结构下,声子分别以波动和粒子性质输运为主;均匀周期超晶格热导率具有显著的尺寸效应和温度效应,而梯度、随机周期Si/Ge超晶格的热导率对样本总长度和温度的依赖性较小.     

Fabrication of nc-Si/SiO2 structure by thermal oxidation method and its luminescence characteristics

Nano-crystalline silicon/silicon oxide （nc-Si/SiO2） structures have been prepared from amorphous silicon films on both silicon and quartz substrates by using electron-beam evaporation approach and annealing at temperatures about 600 ℃ in air. As a thermal oxidation procedure, the annealing treatment is not only a crystallization process but also an oxidation process. Scanning electron microscopy is employed to characterize the surface morphology of the nc-Si/SiO2 layers. Transmission electron microscopy study shows the sizes of nc-Si grains on the two different substrates. The nc-Si/SiO2 structures exhibit visible luminescence at room temperature as confirmed by photoluminescence spectroscopy. Comparing the photoluminescence spectra of different samples, our results agree with the quantum confinement-luminescence center model.     

GaAsN/GaAs量子阱在1 MeV电子束辐照下的退化规律

为研究GaAsN/GaAs量子阱在电子束辐照下的退化规律与机制,对GaAsN/GaAs量子阱进行了不同注量(1×1015,1×1016 e/cm2)1 MeV电子束辐照和辐照后不同温度退火(650,750,850℃)试验,并结合Mulassis仿真和GaAs能带模型图对其分析讨论。结果表明,随着电子注量的增加,GaAsN/GaAs量子阱光学性能急剧降低,注量为1×1015 e/cm2和1×1016 e/cm2的电子束辐照后,GaAsN/GaAs量子阱PL强度分别衰减为初始值的85%和29%。GaAsN/GaAs量子阱电子辐照后650℃退火5 min,样品PL强度恢复到初始值,材料带隙没有发生变化。GaAsN/GaAs量子阱辐照后750℃和850℃各退火5 min后,样品PL强度随退火温度的升高不断减小,同时N原子外扩散使得样品带隙发生约4 nm蓝移。退火温度升高没有造成带隙更大的蓝移,这是由于进一步的温度升高产生了新的N—As间隙缺陷,抑制了N原子外扩散,同时导致GaAsN/GaAs量子阱光学性能退化。     

Annealing effects on residual stress of HfO2/SiO2 multilayers

HfO2/SiO2 multilayer films were deposited on BK7 glass substrates by electron beam evaporation method.The effects of annealing at the temperature between 200 and 400℃ on residual stresses have been studied.It is found that the residual stress of as-deposited HfO2/SiO2 multilayers is compressive.It becomes tensile after annealing at 200℃,and then the value of tensile stress increases as annealing temperature increases.And cracks appear in the film because tensile stress is too large when the sample is annealed at 400℃.At the same time,the crystallite size increases and interplanar distance decreases with the increase of annealing temperature.The variation of residual stresses is corresponding with the evolution of structures.     

(Si,Er)双注入热氧化硅的光致发光

采用强流金属蒸汽真空弧（MEVVA）离子源注入机，先将Si大束流注入热氧化SiO2/单晶硅，直接形成镶嵌在SiO2中的纳米晶Si，再小束流注入Er。Er离子在掺杂层中的浓度可达10^21cm^-3量级，大大地提高了作为孤立发光中心的Er^3 浓度。在77K和室温下，观察到了Er^3 的1.54цm特征发射。     

Structural ordering in a silica glass matrix under Mn ion implantation

Mn(+)-implanted, amorphous SiO(2) samples were synthesized using pulsed-ion implantation without thermal annealing. The crystal and electronic structures have been studied using x-ray diffraction and synchrotron-based soft x-ray absorption and emission spectroscopy at the Si and Mn L(2,3) edges. We find a combination of small MnO clusters and Si crystallites at shallow depths while tetrahedral Mn coordination is found deeper in the host target. Through a combination of techniques, we find that the implantation process simultaneously decreases the long-range order in the near-surface region and increases order deeper in the SiO(2) host. Our results suggest Mn substitution into Si sites at deep levels catalyzes the formation of α-quartz, providing insight into the complex interactions that determine the local structure around the impurities as well as the overall changes to the crystallinity of implanted SiO(2).     

不同成分比例CIGS薄膜及太阳电池的快速退火

研究了110~180 ℃(2 min)下的快速热退火对Cu(In,Ga)Se2(CIGS)薄膜特性及CIGS太阳电池性能的影响.结果表明:对于不同成分比例的CIGS(正常、富Cu、高Ga)电池来说,150 ℃,2 min的快速退火最利于电池性能及二极管特性的增加.其中,退火对富Cu电池的开路电压Voc改善最大,这是因为快速热退火对消除部分CIGS薄膜中的CuSex有积极作用,从薄膜的电阻率有少量提高,器件的短路电流Jsc有少量下降可以得到验证;而对于高Ga电池来说,填充因子FF的改善最大,这是因为高Ga样品的缺陷较多,退火会消除薄膜内部的部分缺陷,从而薄膜的迁移率及Jsc都有所提高,使得FF有较大的增加.     

GaAs/SiO2纳米晶镶嵌薄膜的拉曼光谱与吸收光谱研究

采用射频磁控共溅射与高真空退火相结合的方法,分别在单晶硅片和光学石英玻璃片上制备了ＧａＡｓ／ＳｉＯ２纳米晶镶嵌薄膜样品。激光拉曼光谱的测量结果表明,退火态样品（４００℃,６０ｍｉｎ）的拉曼光谱特征峰呈现宽化和红移,红移量为９．５ｃｍ＾－１,对应薄膜中ＧａＡｓ纳米晶粒平均粒径约为３ｎｍ。样品的室浊吸收光谱测量结果表明,由于受量子限域效应的主导作用,与ＧａＡｓ块状单晶相比,样品光学吸收边呈现出明显的蓝     

等温退火对辐照诱发的非晶TiNiCu合金微观组织结构的影响

 TiNiCu记忆合金在美国Argonne国家实验室IVEM Tandem National Facility加速器产生的400keV Xe+离子辐照到0.4dpa时发生非晶化转变。通过电子显微镜研究了非晶化的TiNiCu合金的回复和再结晶过程。退火加热的速度是10℃/min。在280℃时非晶环附近出现电子衍射斑点以及明场像中出现少量析出相，表明回复和再结晶开始。退火到550℃出现多晶环，650℃时有片状马氏体变体生成，750℃时有很锐利的多晶环出现，表明再结晶过程基本完成。经标定再结晶晶粒仍然是TiNiCu记忆合金。再结晶组织与辐照前TiNiCu 合金的显微组织相比有较大差异。     

不同成分比例CIGS薄膜及太阳电池的快速退火

研究了110~180 ℃（2 min）下的快速热退火对Cu(In,Ga)Se2(CIGS)薄膜特性及CIGS太阳电池性能的影响.结果表明：对于不同成分比例的CIGS（正常、富Cu、高Ga）电池来说,150 ℃,2 min的快速退火最利于电池性能及二极管特性的增加.其中,退火对富Cu电池的开路电压Voc改善最大,这是因为快速热退火对消除部分CIGS薄膜中的CuSex有积极作用,从薄膜的电阻率有少量提高,器件的短路电流Jsc有少量下降可以得到验证|而对于高Ga电池来说,填充因子FF的改善最大,这是因为高Ga样品的缺陷较多,退火会消除薄膜内部的部分缺陷,从而薄膜的迁移率及Jsc都有所提高,使得FF有较大的增加.     

Correlation between impurities in Fe-Si amorphous layers synthesized by Fe implantation and photoluminescence property of β-FeSi2 precipitates in Si

Completely amorphous Fe-Si layers are formed by Fe implantation into Si substrate at a dosage of 5×10¹⁵ cm⁻² using a metal vapor vacuum arc (MEVVA) ion source under 80 kV extraction voltage and cryogenic temperature. After thermal annealing, β-FeSi₂ precipitates are formed in Si matrix. The influence of impurities in these amorphous Fe-Si layers on the photoluminescence (PL) from β-FeSi₂ precipitates is investigated. PL is found to be significantly enhanced by optimizing the impurity concentration and annealing scheme. After 60 s of rapid thermal annealing (RTA) at 900 °C, β-FeSi₂ precipitates in medium boron-doped Si substrate give the strongest PL intensity without boron out-diffusion from them.