三元混晶膜的表面声子极化激元

采用改进的无规元素孤立位移模型和波恩-黄近似,运用电磁场的麦克斯韦方程和边界条件,研究极性三元混晶膜中的表面声子极化激元.以AlxGa1-xAs,ZnxCd1-xS 和GaxIn1-xN 膜为例,获得了其中表面声子极化激元的频率作为波矢和膜厚之函数的数值结果并进行了讨论.结果表明:在三元混晶膜中有四支表面声子极化激元,不同材料的色散曲线分别显示了混晶电磁声子模的"双模"和"单模"特征.     

Surface exciton-polaritons in ternary mixed crystals

The surface exciton-polaritons in ternary mixed crystals are investigated. The numerical calculations for several III-V and II-VI compound systems are performed and the polariton frequencies as functions of the wave-vector and the compositions for ternary mixed crystals AlxGa1-xAs, CdxZn1-xSe and AlxGa1-xN as examples are given and discussed. The results show that the dependence of the energies of surface polaritons on the composition of ternary mixed crystals are slightly nonlinear different from the bulk modes.     

Ga_xIn_(1-x)As单晶的制备及其电学特性

本文叙述利用液封法研制Ga_xIn_(1-x)As单晶的工艺和这种单晶的电学特性.三元合金料用直接合成法制备.拉晶速度为每小时3毫米左右.研制的三元单晶的组分为0.92≤x<1.组分沿单晶的长度方向分布比较均匀.Ga在Ga_xIn_(1-x)As单晶中的分凝系数大于1,并随合金熔体中Ga组元含量降低而增加.室温下Ga_xIn_(1-x)As单晶的载流子浓度和电子迁移率分别为n(?)10~(15)cm~(-3)和μ=4～6×10~3cm~2/V·s.最后讨论了合金散射和晶格失配对晶体性质的影响.     

三元混晶膜的表面激子极化激元

运用麦克斯韦方程组和波恩-黄昆(Born-Huang)近似,对几种典型膜材料的三元混晶(TMC)膜中的表面激子极化激元进行了研究和数值计算。结果表明:TMC膜中存在两支激子极化激元表面模,与二元材料定性类似,但定量明显不同;TMC膜两支表面模频率和分裂能均随组分非线性变化;非线性程度与混晶膜厚(或频率)有关,在某些膜厚(或频率)下,可呈现非单调性。     

CdTe衬底中微细孪晶对Hgl-xCdxTe液相外延层的影响

本文首次报导了作为 Hg_(1-x)Cd_xTe 液相外延衬底的 CdTe 晶片中存在着狭窄的微细孪晶,其宽度由数十微米到数微米。这些微细孪晶在液相外延过程中将向Hg_(1-x)Cd)_xTe 外延层延伸,形成相应的 Hg_(1-x)Cd_xTe 微细孪晶,从而导致外延层表面出现细长的直线线痕,程度不同地破坏了 Hg_(1-x)Cd_xTe 液相外延层表面的平整性和光洁度。     

Ternary phase relations in the vicinity of chalcopyrite copper gallium sulfide

Some of the ternary phase relationships relevant to the growth of Cu_1-x Ga_1-x/3 -S₂ chalcopyrite crystals have been studied by DTā, TGA, x-ray powder diffraction, lattice parameter measurements, scanning electron microscopy and optical absorption. The extensive existence region of the compound (0 ≤ x ≤ O.1645) was verified and some evidence for extensive sulfur solubility at x = 0 obtained. The dystectic (maximum melting) composition was obtained from a melt of about 53 at% S, 25 at% Ga, and 21 at% Cu. Conditions necessary for the growth of stoichiometric crystals which are free of Cu_xS precipitates and the associated green coloration are given. Such compositions are necessary for the generation of luminescence in this compound. Work performed while a resident at Bell Laboratories     

AxB1-xCyD1-y型四元混晶光学声子性质的研究

针对现有理论的不足,提出了新的AxB1-xCyD1-y型四元混晶中晶格振动理论模型,利用Clausius-Mossotti公式对运动方程组加以简化,同时引入波恩-黄昆方程消除微观变量,最终得到混晶声子频率对组分（x、y）的依赖关系。该理论模型优点在于只需知道AC、AD、BC和BD四种二元混晶的若干参数（光学声子横模频率、纵模频率和晶体的静态介电常数和光学介电常数）,就可求出AxB1-xCyD1-y型四元半导体混晶的光学声子特性,当组分取边界值时,结果则对应三元和二元晶体。理论结果与实验数据符合较好,对今后实验有一定指导作用。     

PSKNN铁电单晶及其激光法生长

采用改进的激光加热基座法 (LHPG)生长出了位于准同形相界附近的含有 Pb元素的钨青铜结构的铁电晶体 (1- x) Pb2 KNb5O15- x Sr2 Na Nb5O15(PSKNN)。通过调节激光功率和陶瓷源棒中 Pb O的含量 ,有效地控制和补偿了晶体生长过程中 Pb O的挥发。通过选择适当的籽晶 ,可以得到沿 [0 0 1],[10 0 ]和 [110 ]方向生长的 PSKNN晶体。研究了所生长晶体的铁电、介电和压电性质 ,并对其准同形相界进行了初步的讨论。     

Structural Origins for Tunable Open‐Circuit Voltage in Ternary‐Blend Organic Solar Cells

Ternary‐blend bulk‐heterojunction solar cells have provided a unique opportunity for tuning the open‐circuit voltage (V_oc) as the “effective” highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO) energy levels shift with active‐layer composition. Grazing‐incidence X‐ray diffraction (GIXD) measurements performed on such ternary‐blend thin films reveal evidence that the two polymer donors interact intimately; their ionization potentials are thus reflections of the blend compositions. In ternary‐blend thin films in which the two polymer donors do not interact physically, the polymer donors each retain their molecular electronic character; solar cells constructed with these ternary blends thus exhibit V_ocs that are pinned to the energy level difference between the highest of the two lying HOMO and the LUMO of the electron acceptor. These observations are consistent with the organic alloy model proposed earlier. Quantification of the square of the square‐root differences of the surface energies of the components provides a proxy for the Flory–Huggins interaction parameter for polymer donor pairs in these ternary‐blend systems. Of the three ternary‐blend systems examined herein, this quantity has to be below 0.094 in order for ternary‐blend solar cells to exhibit tunable V_oc.     

三组三元合金异质结的价带带阶

采用基于LMTO－ASA的平均键能计算方法和原子集团展开方法，研究了三组典型的晶格匹配三元合金异质结（GaAs）x（Ge2）1-x／GaAs，（AlAs）x（Ge2）1-x／GaAs和AlxGa1-xAs／GaAs的价带带阶△Ev（x）值。研究表明：AlxGa1-xAs／GaAs异质结的Mv（x）值随合金组分x的变化接近于线性；（GaAs）x（Ge2）1-x／GaAs和（AlAs）x（Ge2）1-x／GaAs的△Ev（x）值随合金组分x的变化是非线性的。△Ev（x）的理论计算值与实验结果相当符合。     

Ga_(1-x)Al_xP混晶的长波长光学声子谱

本文报道Ga_(1-x)Al_xP混晶的室温喇曼散射测试结果。所用的样品用液相外延方法生长在〈111〉晶向的GaP衬底上。混晶组分x值在0.16—0.65之间。实验结果表明,Ga_(1-x)Al_xP混晶的长波长光学声子谱呈现双模行为,具有类GaP和类AIP两个光学支。     

硫掺杂对ZnO热电性能的影响

采用固相反应法制备了ZnO1-xSx块体材料(0≤x≤0.05);通过对样品X射线衍射谱(XRD)、电导率和Seebeck系数的测量,研究了S掺杂对ZnO晶体结构及热电性能的影响。结果表明:所有试样均为六方纤锌矿结构。在573 K时,ZnO1-xSx(0相似文献   

布里奇曼法生长的Hg1—xCdxTe晶体的性能

本文简要地介绍了布里奇曼法生长的Hg_(1-x)Cd_xTe晶体的组分分布、电学性质、微观结构和红外透射比曲线。这些晶体具有较好的横向组分均匀性、较低的载流子浓度和较长的少数载流子寿命。本文还报道了用此晶体制作的光电导器件的性能。     

氢钝化对Hg1—xCdxTe红外透射谱的影响

采用红外透射测量观测了氢钝化对Ｈｇ１－ｘＣｄｘＴｅ晶片的影响，用分层模型计算了晶片射率，分析了氢钝化增加其透射率，吸收边向短波方向移动，低于禁带宽度能量的吸收降低，透过范围减小的原因。表明氢钝化不仅影响到表面，而且影响到整个体内。原因是经氢钝化处理后杂质或缺陷受到有效钝化，载流子浓度降低，组分Ｘ增加；荷电杂质或缺陷的局域内场影响发失变化；以及荷电杂质或缺陷散射增强。     

Bi基BNT-BKT-BiFeO_3陶瓷的准同型相界和电性能

采用固相反应法,制备了Bi基(1–x–y)(Bi0.5Na0.5)TiO3-x(Bi0.5K0.5)TiO3-yBiFeO3(x=0.12～0.24,y=0～0.07)钙钛矿型三元系无铅压电陶瓷,研究了该陶瓷组分与其晶相结构、电性能的关系。结果表明:除x=0.24,y=0.03的组分析出第二相外,其他组分均能形成纯钙钛矿固溶体,陶瓷三方、四方相共存的准同型相界(MPB)组分范围为x=0.18～0.21,y=0～0.05。在MPB附近陶瓷具有较好的压电性能,其d33和kp在x=0.18,y=0.03达到最大值:d33=171pC/N,kp=0.366。     

单晶炉温场分布对碲镉汞晶体结构的影响

本文论述了不同炉温分布,对比研究温场对碲镉汞晶体结构的影响。     

Influence of native defects on the infrared transmission of undoped Ga<Subscript>1−x</Subscript>In<Subscript>x</Subscript>Sb bulk crystals

The below bandgap infrared transmission (up to 25 μm) in undoped Ga_1−xIn_xSb bulk crystals has been studied for the first time and found to be limited by native defects such as antisites and vacancies found in antimonide-based III–V compounds. For the gallium-rich alloy compositions (x<0.5 in Ga_1−xIn_xSb), the crystals exhibit p-type conductivity with an increase in net acceptor concentration and an increase in gallium content in the crystals. For x>0.5 (the indium-rich alloy compositions), the crystals exhibit n-type conductivity when the net donor concentration and indium content in the crystals increase. A correlation between the optical transmission and the residual carrier concentration arising from the native acceptors and donors has been observed. Due to donor-acceptor compensation, crystals with alloy compositions in the range of x=0.5−0.7 exhibit high optical transmission for a wide wavelength range (up to 22 μm). The light hole to heavy hole interband transition in the valence band and the free electron absorption in the conduction band have been found to be the two dominant absorption processes.     

Electrochemical pore formation mechanism in III–V crystals (Part I)

The anodic behavior of III–V crystals in electrolyte solutions was experimentally studied. The dependences of the pore-formation threshold voltage on the semiconductor composition and doping level, electrolyte solution composition and concentration, as well as the crystallographic orientation of the anodized surface, were obtained. Chemical and phase compositions of pore-formation reaction products in various semiconductor-electrolyte systems were studied. The structure of porous layers formed in GaAs, InP, and GaP crystals in aqueous and nonaqueous solutions was studied. The conditions for anisotropic propagation of pores in these crystals in the 〈111〉V and 〈111〉III directions were determined. The results obtained show that there is a fundamental difference of the chemical mechanisms of pore-formation reactions from mechanisms of anodic etching of III–V compounds.     

制备工艺对PMN铁电陶瓷性能的影响

从材料组成、结构和性能的关系出发,系统地研究了探讨了制备工艺对弛豫型铁电陶瓷性能的影响,以及烧结后退火工艺对样性能的影响。研究PbTiO3组分2种不同的加入方式((1-x)(PbO 1/3MgNb2O6) x(PbO TiO2)和(1-x)(PbO 1/3MgNb2O6) x(PbTiO3))对Pb(Mg1/3Nb2/3)O3-PbTiO3固溶体陶瓷介电性能的影响规律。与用前一种方法制得的试样相比,用后一种方法得到的陶瓷试样的介电常数峰得到进一步展宽,并且呈现双峰。介电性能的这种变化表明微区化学组成的均匀程度对材料的宏观介电性能会产生显著影响。     

Transformation of the habit of natural diamond crystals during activation of nonequilibrium processes

The possibility of the appearance of irreversible strongly nonequilibrium phenomena in diamond crystals with the use of algorithms of the combined wave effect is shown in principle. The experimental procedure for inducing considerable high-energy fluctuations of the exciting wave field in diamond and, as a consequence, for forming both surface and bulk dissipative structures during the effect is described. Surface structures manifest themselves as the regularity of the morphological motive of the surface layer. Bulk structures are caused by the transformation of the crystalline structure of the material. Experimental results on the purposeful transformation of the shape of diamond crystals are presented and discussed.