自发有序Ga0.5In0.5P合金的静压光致发光研究

在０—７ＧＰａ静压范围内测量了自发有序Ga_0.5In_0.5P合金的室温光致发光谱．三块样品的常压带隙能量分别比无序样品低１１５，９２和４３ｍｅＶ，它们的压力系数也从无序样品的９２ｍｅＶ／ＧＰａ分别减小到７５，８１和８３ｍｅＶ／ＧＰａ．用Γ-Ｌ相互作用模型可以同时解释有序合金的带隙能量的降低以及压力系数的减小．得到的Γ-Ｌ相互作用势分别为０.１９，０.１５和０.１０ｅＶ．表明在自发有序Ga_0.5In_0.5P合金中存在着的     

非线性光学晶体HgGa2S4 和 Hg0.5Cd0.5Ga2S4的能带结构、化学键及光学性质研究

用密度泛函理论和非谐振子模型计算了晶体HgGa₂S₄和Hg_0.5Cd_0.5Ga₂S₄的能带结构、态密度、化学成键及线性、非线性光学性质。结果表明：HgGa₂S₄的价带顶部主要是Ga-S成键态的贡献，导带底部主要是Ga-S反键态的贡献; Hg_0.5Cd_0.5Ga₂S₄的价带顶部主要由S-3p轨道组成，导带底部主要是Ga-S反键态的贡献。布居分析表明Ga-S键主要是共价成分，而Hg-S和Cd-S键主要是离子成分。HgGa₂S₄的折射率计算值与实验值在低能量区很好吻合。另外，HgGa₂S₄的能隙计算值比Hg_0.5Cd_0.5Ga₂S₄小，而二阶非线性极化率比Hg_0.5Cd_0.5Ga₂S₄大。     

GaInP材料生长及其性质研究

用常压MOCVD在半绝缘GaAs衬底上生长了Ga_xIn_1-xP(x=0.476～0.52)外延层,对外延层进行了X光双晶衍射、Hall和光致发光(PL)测试.77K下电子迁移率达3300cm²/V.s(浓度为1.4×10¹⁶cm^-3).载流子浓度随生长温度升高,随Ⅴ/Ⅲ比的增大而降低,并提出P空位(V_p)是自由载流子的一个重要来源,17KPL谱中,Ga_0.5In_0.5P(Tg=650℃,Ⅴ/Ⅲ=70)的峰能为1.828eV,半峰宽为19meV.另外,在1.849eV处还有一较弱的峰,GaInP峰能和其计算的带隙最大相差113meV,这可能与GaInP中杂质或缺陷以及其中存在有序结构有关.     

InxGa1－xAs缓冲层上InyGa1－yAs/(Al)Ga

本文中,发现在In_xGa_1-xAs缓冲层上非故意掺杂的In_yGa_1-yAs/(Al)GaAs超晶格样品中存在着两个互相反向的自建电场区,一个位于样品表面,另一个位于In_xGa_1-xAs缓冲层和超晶格界面。据此,合理地解释了样品的光伏测试结果,并对此类样品的MOCVD生长工艺给予指导。     

1.55μm InGaAsP/InP应变量子阱激光器的LP－MOCVD生长

本文首次报导了生长温度为550℃,以三甲基镓(TMGa)和三甲基铟(TMIn)为Ⅲ族源,用低压金属有机物气相沉积(LFMOCVD〕技术,高质量1.62um和1.3umInGaAsP及In_0.57Ga_0.43As_0.98P_0.04/In_0.73Ga_0.27As_0.6P_0.4量子阶结构的生长,并给出了1.55umGaAsP/InP分别限制应变量子阱结构激光器的生长条件,激光器于室温下脉冲激射,其阈值电流密度为2.4kA/cm².     

InAlAs/InGaAs/InAlAs量子阱高迁移率二维电子气系统中的反弱局域效应研究

研究了Si 重δ 掺杂In_0.52Al_0.48As/In_0.53Ga_0.47As/In_0.52Al_0.48As单量子阱内高迁移率二维电子气系统中的反弱局域效应. 研究表明，强的Rashba自旋轨道相互作用来源于量子阱高的结构反演不对称. 高迁移率系统中，粒子的运动基于弹道输运而非扩散输运. 因此，旧的理论模型不能用于拟合实验结果. 由于最新的模型在实际拟合中过于复杂，一种简单可行的近似用于处理实验结果，并获得了自旋分裂能Δ₀和自旋轨道耦合常数α两个重要的物理参数. 该结果与对纵向电阻的Shubnikov-de Haas—SdH振荡分析获得的结果一致. 高迁移率系统中的反弱局域效应研究表明，发展有效的反弱局域理论模型，对于利用Rashba自旋轨道相互作用来设计自旋器件尤为重要.     

V2Ga5的晶体结构

本文利用单晶与粉末衍射方法测定了V₂Ga₅的晶体结构。V₂Ga₅属四方晶系,其单相区约为VGa₂—V₂Ga₅。在18℃的点阵常数是a=8.9540?,c=2.6892?,每个晶胞含有二个化合式量,空间羣为D_4h⁵—P4/mbm。V原子与Ga原子分别占据在4(h)与8(i),2(d)的等效位置上。参数为:x相似文献   

He+辐照对Ga0.94Mn0.06As薄膜铁磁性的改善

离子辐照半导体可以很好的改善半导体材料的磁学性质.用He⁺ 辐照Ga_0.94Mn_0.06As薄膜,可以较方便的调制Ga_0.94Mn_0.06As 薄膜中产生铁磁性载体的浓度.由于空穴居间而导致Ga_0.94Mn_0.06As薄膜的铁磁性, 可以通过He⁺的辐照来得到改善,其结果是Ga_0.94Mn_0.06As薄膜的矫顽力可以增加3倍多. 当He⁺辐照流强增加时, 居里温度和沿着样品面外磁化难轴方向的饱和磁场都减小了. 被辐照的Ga_0.94Mn_0.06As薄膜的电学性质和结构特征显示, He⁺辐照Ga_0.94Mn_0.06As薄膜可以有控制地改善它的铁磁性, 其结果源于He⁺辐照Ga_0.94Mn_0.06As薄膜所诱导产生电缺陷对空穴的补偿, 而不是He⁺辐照改变了Ga_0.94Mn_0.06As薄膜的结构.     

In2O3 透明薄膜晶体管的制备及其电学性能的研究

采用磁控溅射方法在玻璃衬底上生长了In₂O₃晶体薄膜.该薄膜具有(111)晶面择优取向,晶粒尺寸达到33 nm.利用光刻工艺制作了以In₂O₃晶体薄膜为沟道层的底栅式薄膜晶体管.In₂O₃薄膜晶体管具有良好的栅压调制特性,场效应迁移率达到6.3 cm²/(V·s),开关电流比为3×10³,阈值电压为-0.9 V.结果表明,In相似文献   

共轭低聚物中光生分子间电荷转移态的第一性原理研究

本文基于第一性原理中的Heyd-Scuseria-Ernzerh方法研究了单层In_1-xGa_xN的电子结构和光学性质.计算得到单层In_1-xGa_xN的能带结构和态密度（DOS）,发现随着掺杂比例的变化,体系带隙的变化范围是1.8~3.8 eV,表明通过Ga的掺杂可以实现体系带隙值的调节.并且还研究了单层In_1-xGa_xN的介电函数,折射率和吸收系数等光学性质,结果表明随着Ga掺杂浓度的增加,介电函数谱的主峰和吸收谱发生了显著的蓝移.此外,基于能带结构和态密度图谱,对单层In_1-xGa_xN的光学性质进行分析,预测这种材料独特的光学性质在纳米电子学和光学器件中会有广泛的应用.     

自发有序Ga_（0．5）In_（0．5）P合金的拉曼光谱研究

自发有序Ｇａ＿（０．５）Ｉｎ＿（０．５）Ｐ合金的拉曼光谱研究李国华，刘振先，韩和相，汪兆平，董建荣（中国科学院半导体研究所，半导体扭晶格国家重点实验室北京１０００８３）（中国科学院半导体研究所，半导体材料科学实验室北京１０００８３））ＲａｍａｎＳｃａ...     

Fang–Howard wave function modelling of electron mobility in AlInGaN/AlN/InGaN/GaN double heterostructures

To study the electron transport properties in InGaN channel-based heterostructures,a revised Fang-Howard wave function is proposed by combining the effect of GaN back barrier.Various scattering mechanisms,such as dislocation impurity(DIS) scattering,polar optical phonon(POP) scattering,piezoelectric field(PE) scattering,interface roughness(IFR) scattering,deformation potential(DP) scattering,alloy disorder(ADO) scattering from InGaN channel layer,and temperature-dependent energy bandgaps are considered in the calculation model.A contrast of AlInGaN/AlN/InGaN/GaN double heterostructure(DH) to the theoretical AlInGaN/AlN/InGaN single heterostructure(SH) is made and analyzed with a full range of barrier alloy composition.The effect of channel alloy composition on InGaN channel-based DH with technologically important Al(In,Ga)N barrier is estimated and optimal indium mole fraction is 0.04 for higher mobility in DH with Al_(0.4)In_(0.07)Ga_(0.53)N barrier.Finally,the temperature-dependent two-dimensional electron gas(2 DEG) density and mobility in InGaN channel-based DH with Al_(0.83)In_(0.13)Ga_(0.0)4 N and Al_(0.4)In_(0.07)Ga_(0.53)N barrier are investigated.Our results are expected to conduce to the practical application of InGaN channel-based heterostructures.     

缓冲层生长温度对In0.82Ga0.18As 薄膜结构及电学性能的影响

采用低压金属有机化学气相沉积(LP-MOCVD)技术,两步生长法在InP衬底上制备In_0.82Ga_0.18As材料。研究缓冲层的生长温度对In_0.82Ga_0.18As薄膜的结构及电学性能的影响。固定外延薄膜的生长条件,仅改变缓冲层生长温度(分别为410,430,450,470 ℃),且维持缓冲层其他生长条件不变。用拉曼散射研究样品的结构性能,测量四个样品的拉曼散射光谱,得到样品的GaAs的纵向光学(LO)声子散射峰的非对称比分别为1.53,1.52,1.39和1.76。测量样品的霍耳效应表明,载流子浓度随缓冲层生长温度变化而改变,同时迁移率也随缓冲层生长温度变化而改变。通过实验得出:缓冲层的生长温度能够影响In_0.82Ga_0.18As薄膜的结构及电学性能。最佳的缓冲层生长温度为450 ℃。     

Spectral response modeling and analysis of p-n-p In_(0.53)Ga_(0.47)As/InP HPTs

We report our results on the modeling of the spectral response of the near-infrared(NIR) lattice-matched p-n-p In_(0.53)Ga_(0.47)As/InP heterojunction pbototransistors(HPTs).The spectral response model is developed from the solution of the steady state continuity equations that dominate the excess optically generated minority-carriers in the active regions of the HPTs with accurate boundary-conditions.In addition,a detailed optical-power absorption profile is constructed for the device modeling.The calculated responsivity is in good agreement with the measured one for the incident radiation at980 nm,1310 nm,and 1550 nm.Furthermore,the variation in the responsivity of the device with the base region width is analyzed.     

Hydrodynamic simulation of chaotic dynamics in InGaAs oscillator in terahertz region

Hydrodynamic calculations of the chaotic behaviors in n^+nn^+In0.53Ga0.47As devices biased in terahertz(THz)electric field have been carried out.Their different transport characteristics have been carefully investigated by tuning the n-region parameters and the applied ac radiation.The oscillatory mode is found to transit between synchronization and chaos,as verified by the first return map.The transitions result from the mixture of the dc induced oscillation and the one driven by the ac radiation.Our findings will give further and thorough understanding of electron transport in In0.53Ga0.47As terahertz oscillator,which is a promising solid-state THz source.     

MOCVD-GaxIn1-xAsyP1-y/InPDBR结构的晶格振动

利用微区Raman散射技术研究了MOCVD-Ga_xIn_1-xAs_yP_1-y/InPDBRs结构的晶格振动。在InP衬底上生长的与InP晶格匹配的四元合金Ga_0.4In_0.6As_0.85P_0.15中包含三种主要的振动模式,分别归属于类InAs、类GaAs和类GaInP。随着Ga_0.4In_0.6As_0.85P_0.15与InP交替生长构成的DBRs结构周期数增加,Raman散射谱中三种振动模式的谱线线型发生明显变化,类InAs振动强度不变,谱线窄化,峰值位置向低频方向移动,类GaAs和类GaInP振动强度逐渐减弱。同时类InAs与类GaAs振动强度比增大。Raman散射研究中声子的限制效应表明多层结构生长过程中界面存在非完整晶态。     

1.3-μm InAs/GaAs quantum dots grown on Si substrates

We compare the effect of InGaAs/GaAs strained-layer superlattice(SLS) with that of GaAs thick buffer layer(TBL)serving as a dislocation filter layer. The InGaAs/GaAs SLS is found to be more effective than GaAs TBL in blocking the propagation of threading dislocations, which are generated at the interface between the GaAs buffer layer and the Si substrate. Through testing and analysis, we conclude that the weaker photoluminescence for quantum dots(QDs) on Si substrate is caused by the quality of capping In_(0.15)Ga_(0.85)As and upper GaAs. We also find that the periodic misfits at the interface are related to the initial stress release of GaAs islands, which guarantees that the upper layers are stress-free.     

自发有序Ga_（0．5）In_（0．5）P合金的喇曼光谱研究

在室温和非共振条件下测量了自发有序Ｇａ０．５Ｉｎ０．５Ｐ合金的喇曼散射谱。测得的３８０，３６０和３３０ｃｍ－１附近的三个散射峰分别归结于合金中的类ＧａＰ的ＬＯ模、类ＩｎＰ的ＬＯ模和ＴＯＭ。发现有序合金的类ＧａＰ的ＬＯ模的声子频率随着合金的带隙能量的降低而增大。认为这与在有序合金中形成沿［１１１］方向的（ＧＳＰ）１／（ＩｎＰ）１单层超晶格有一定联系。在几种偏振配置下测得的有序合金的喇曼谱的偏振特性与通常的闪锌矿结构的半导体材料的偏振特性类似。     

Dielectric loss of half-doped manganite La_(0.5)Ca_(0.5)MnO_3

The dielectric loss tanδ of half-doped manganite La 0.5 Ca 0.5 MnO 3 is investigated using Green's function technique. The La 0.5 Ca 0.5 MnO 3 is described by the Kondo-lattice model in the double exchange limit, taking into account the Jahn-Teller distortion and the super-exchange interaction between the localized electrons. It is found that the intensity of tanδ decreases with increasing | ε JT |, V, and U. It is also observed that the transition temperature T P rises as | ε JT | and U increase. It is worth noting that T P remains unchanged and the strength of tanδ increases with increasing g. The calculated dielectric loss results are explained theoretically, and these behaviors are in qualitative agreement with the experimental results.