The Investigation of Bulk and Surface Polariton Modes in Ga1?xNxAs by Using Infrared Magneto Spectroscopy

We present and discuss infrared magnetoplasma reflectivity and surface polariton modes in Ga_1–xN_xAs. It assumed that the sample is characterized by a magnetoplasma dielectric tensor. Surface polariton dispersion for two component magnetoplasma was calculated from reflectivity spectra data. We detect transverse optic phonon of GaN sublattice in 470 cm^-1. The origin of sharp feature in p-polarization reflectivity about 300 cm^–1 as well as LO phonon frequency of GaAs sublattice is due to Brewster mode. An interesting feature of surface modes in Voigt geometry is nonreciprocalicity, which means that the frequency changes when the direction of propagation is reversed. Also, the infrared magnetoplasma reflectivity of GaNAs should be providing determination of the electrons and heavy holes effective mass and carrier's concentration.     

液相外延GaAs1-xPx混晶的光学声子、等离子体激元和LO声子-等离子体激元耦合模

在40—700cm^-1波数和4.2—300K温度范围内研究了不同组份液相外延n型CaAs_1-xP_x样品的红外反射谱。对反射谱进行了赝谐振子拟合与K-K关系计算。从而获得了有关描述CaAs_1-xP_x样品的光学声子模、等离子体激元、LO声子-等离子体激元耦合模的重要物理参量及红外光学常数信息。基于这些计算结果,提出了双导带谷并计及与X能谷相联系的施主能级模型,用它解释等离子体激元频率和实验观察的三支主要的耦合模的温度变化规律。 关键词：     

Far Infrared Investigation of Plasmon-LO Phonon Coupling and Surface Polaritons Modes in Donor Doped Cd1-xHgxTe and CdTe Thin Layer on GaAs Substrate

Infrared Fourier transform spectroscopy has been used to investigate phonon and plasmon modes in Cd_1-xHg_xTe and CdTe thin layer on GaAs substrate. Attenuated total reflection (ATR) spectroscopy has been used to excite surface plasmon and phonon polaritons. The plasmon-LO phonon coupling modes in samples are studied by dispersion curve calculation for various carrier concentrations. There exist three branches of coupled modes in dispersion curve. For analysis of the far infrared polarized reflectivity spectra we employ the harmonic oscillator dielectiic function model and the Drude model for free carrier response. We find that the coupling modes dependent to the concentration of free carriers. Furthermore, the experimental data have been used to calculate carrier concentration, composition parameter, mobility of carrier, thickness of layer and gap energy.     

CdxHg1-xTe混晶声子谱的远红外光谱研究

在温度4.2—300K和波数15—5OOcm^-1的范围内研究了x=0.18到0.45的不同组分的Cd_xHg_1-xTe的远红外吸收光谱。除剩余射线吸收带两侧的双声子吸收结构外,实验首次观察到一个位于波数20—50cm^-1的低频吸收带。用面间力常数的密度函数法等估计了Cd_xHg_1-xTe混晶的声子谱,并将上述低频吸收带归之于混晶导致的无序和“掺杂”诱发TA声子带模吸收效应。 关键词：     

Far-infrared spectra of Pb1−xMnxTe alloys

Far-infrared reflectivity spectra of Pb_1−xMn_xTe (0.0001x0.1) single crystals were measured in the 10–250 cm⁻¹ range at room temperature. The analysis of the far-infrared spectra was made by a fitting procedure based on the model of coupled oscillators. In spite of the strong plasmon–LO phonon interaction, we found that the long wavelength optical phonon modes of these mixed crystals showed an intermediate one–two mode behavior.     

Hg1-xMnxTe远红外反射光谱

本文报道不同组份Hg_1-xMn_xTe材料在4.2—300K温度范围内的远红外反射光谱。观察别由Mn诱发的高频局域模以外另一个与Mn相关的禁带模,它的频率为97cm^-1。在理论上分析计算了这一新振动模行为。 关键词：     

Sb掺杂Hg1-xCdxTe的光致发光

对不同Sb掺杂浓度Hg_1-xCd_xTe（x≈0.38）样品在3.9—115K的温度范围内进行了光致发光实验测量，观察到与局域激子、带到带和施主受主对有关的辐射复合过程．并用光致发光手段发现Sb掺杂在x≈0.38的Hg_1-xCd_xTe中引入的约30meV的受主能级 关键词：     

AlxGa1-xAs俄歇灵敏度因子的测定

利用PHI610俄歇谱仪测定了Al,Ga和As的俄歇灵敏度因子。对6种不同x值的Al_xGa_1-xAs样品进行俄歇定量分析。结果与X射线双晶衍射测量值非常一致。结果表明,利用自身谱仪测定的俄歇灵敏度因子进行的定量分析结果,与目前通常使用的手册或内标法提供的元素相对灵敏度因子的定量分析结果相比,测量精度得到大大提高。 关键词：     

GaAs/AlxGa1-xAs超晶格子带间光跃迁的研究

运用Kronig-Penney模型的新形式,研究了超晶格子带间光跃迁的频率、带宽和跃迁强度,用GaAs/Al_xGa_1-xAs多量子阱材料做了关于红外吸收的实验,理论与实验符合较好。 关键词：     

六方相InGaN外延膜的显微Raman散射

用X射线衍射(XRD)技术和显微Raman散射方法对金属有机化学气相沉积(MOCVD)法生长的六方相In_xGa_1-xN薄膜样品进行了研究，观察到了相分离现象和LO声子-等离子耦合模(LPP⁺)，讨论了In_xGa_1-xN的A₁(LO)模被屏蔽的主要物理机制.同时，对Raman谱中E₂和A₁(TO)声子模进行了分析和讨论.在In_xGa_1-xN样品的低温Raman谱中还观察到单电子跃迁产生的Raman散射信号. 关键词： Raman散射 X射线衍射 相分离 应力 LO声子-等离子耦合     

Infrared vibrational spectra of l-histidinium dihydrogen orthophosphate orthophosphoric acid (LHP)

The entire vibrational spectrum of a single crystal of l-histidinium dihydrogen orthophosphate orthophosphoric acid (LHP) was studied by infrared (IR) spectroscopy from 10 up to 4000 cm⁻¹. The polarized infrared (IR) reflectivity spectra were measured between 7 and 250 K, in the frequency range 10–600 cm⁻¹. From the IR spectral analysis, the phonon modes were classified within their symmetry species, and their longitudinal (LO) and transversal (TO) optical frequencies were calculated. A tentative assignment of the various internal modes observed in the transmissivity spectrum of LHP, between 300 and 4000 cm⁻¹, is proposed. The present study did not reveal any low-temperature structural phase transition.     

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。     

GaAs/AlxGa1-xAs量子阱红外探测器微结构研究

采用金属有机物化学气相沉积法生长了两种不同结构参数GaAs/AlxGa1-xAs量子阱材料。利用傅里叶光谱仪分别对势垒中Al组分为0.20,0.30的1#,2#样品进行77 K液氮温度下光谱响应测试。结果显示:1#,2#峰值响应波长为8.38,7.59 m,而根据薛定谔方程得到峰值波长为9.694,8.134 m,二者误差分别为13.6%,6.68%。针对误差过大及吸收峰向高能方向发生漂移的现象,利用高分辨透射扫描电镜对样品微观界面结构进行分析,结果显示,样品存在不同程度的位错及不均匀性。结果表明:位错引起AlGaAs与GaAs晶格不匹配,是造成1#误差较大的主要原因;峰值响应波长随势垒中Al组分的降低而增大,说明Al组分减小致使量子阱子带间距离缩小是导致峰值响应波长红移的原因。     

GaN1-xPx薄膜的结构特性研究

用金属有机物化学气相沉积技术在蓝宝石衬底上外延了高P组分的GaN_1-xP _x 薄膜.利用x射线衍射仪和拉曼光谱仪研究了P对GaN_1-xP_x晶体结构 的影响.研究结果表明：随着P组分比的增加，GaN_1-xP_x（0002）衍射 峰逐渐向小角度移动，即晶格常数变大；与非掺杂GaN相比，GaN_1-xP_x薄 膜的拉曼光谱中出现了4个新的振动模 关键词： 1-xP_x')" href="#">GaN_1-xP_x 金属有机物化学气相沉积 x射线衍射 拉曼光谱     

Structural properties of Bi1-xLaxFeO3 studied by micro-Raman scattering

This paper reports that La-doped BiFeO 3(Bi1-x La x FeO3,x = 0,0.1,0.2,0.3,0.6,0.8 and 1.0) were studied by using micro-Raman spectroscopy and x-ray diffraction(XRD).The XRD patterns indicate that the structure of Bi1-xLaxFeO 3 changes from rhombohedral BiFeO3 to orthorhombic LaFeO3.The results of Raman spectroscopy show good agreement with the XRD results.Strikingly,the phonon peak at around 610 cm-1 and the two-phonon peaks in the high frequency range exist in all compounds and enhance with increasing La substitution.The increasing intensity of the 610 cm-1 peak is attributed to the changes in the FeO 6 octahedron during the rhombohedral-orthorhombic phase transition.The enhancements of the two-phonon peaks are associated with the breakdown of the cycloid spin configuration with the appearance of the orthorhombic structure.These results indicate the existence of strong spin-phonon coupling in Bi1-xLax FeO3,which may provide useful information for understanding the effects of La content on the structural and magnetic properties of Bi1-xLaxFeO3.     

TiN和Ti1-xSixNy薄膜的微观结构分析

使用x射线衍射(XRD)、x射线光电子谱(XPS)、高分辨透射电子显微镜(HRTEM)和原子力显微镜（AFM）多种观测手段分析了TiN薄膜和Ti_1-xSi_xN_y纳米复合薄膜的微观结构.实验分析证明Ti_1-xSi_xN_y薄膜是由直径为3—5nm的纳米晶TiN和非晶Si₃N₄相构成，并且Ti_1-xSi_{x关键词： 纳米复合薄膜 自由能 表面粗糙度 TiN 1-x}Si_xN_y')" href="#">Ti_1-xSi_xN_y     

Cd1-xMnxTe混晶的远红外吸收光谱

本文报道4.2—300K和20—400cm^-1范围内不同组份的Cd_1-xMn_xTe混晶远红外声子吸收光谱的研究结果。实验分辨了类CdTe,类MnTe剩余射线带及其TO-LO分裂,首次观察到位于混晶剩余射线吸收区内侧的低频吸收带、低x值情况下的准定域模吸收峰及其两侧的诸双声子吸收带。用缺陷晶格动力学理论估计了准定域模的出现及位置,讨论了其他吸收带的物理起源和判定。 关键词：     

Optical properties of AlxGa1-xAs/GaAs MQW studied by infrared ellipsometry and fourier transform infrared spectroscopy

The optical response of Al_xGa_1-xAs/GaAs MQW from near-infrared to far-infrared has been studied. Using infrared spectroscopic ellipsometry, we measured the optical response of the samples in the energy range 0.5-2.0eV, and oscillations have been observed. A multilayer film calculation indicates that this phenomenon results from interference. By Fourier transform infrared spectroscopy, the absorptance of double-well MQW has been measured in the energy range 0.08-0.25eV. The energy levels of subbands and the oscillator strengths were calculated from self-consistent interface potential theory. The calculation results are consistent with the measurements.     

高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长

用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份Al_xGa_1-xAs（其x值达0.83）,和Al_xGa_1-xAs/GaAs/Al_xGa_1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n_300K=1.7×10¹⁵cm^-3,n_77K=1.4×10¹⁵cm^-3,迁移率μ_300K=5900cmcm²/V.S,μ_77K=55500cm²/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。     

Exciton-phonon coupling in indirect AlxGa1−xAs

Several persistent high-energy peaks in the photo-luminescence spectrum of indirect Al_xGa_1?xAs are reported. These transitions are assigned to zero-phonon and phonon-assisted bound-exciton annihilation processes. Symmetry determined selection rules indicate that the major interband recombination mechanism is due to LO phonon scattering of electrons near X(100) to the energetically adjacent Γ^CB₁ (000) intermediate state. Scattering associated with alloy disorder may also contribute to the spectrum. The change in the phonon-assisted spectra at x = 0.43 ± 0.01 provides an additional means of identification of the direct-indirect conduction band crossover.