BSO晶体电光效应的实验研究

本文研究了含有自然旋光的BSO晶体的电光效应,并采用自然旋光与电光相移相补偿的方法和调制度函数法测量了不同生长条件下BSO晶体的半波电压。     

布里渊光时域反射计中电光调制器的调制特性与控制

在布里渊光时域反射计（BOTDR）中,电光调制器（EOM）的工作点会随着外部环境变化而发生漂移,这将影响BOTDR系统的测量精度及测量稳定性。本文在分析BOTDR系统中EOM调制特性的基础上,提出了一种控制EOM工作点的方法,使用数字信号处理器作为控制核心,采用＂步进跟随＂的算法。实验结果表明,本文方法可以使EOM长期...     

Synthesis,growth and physical properties of silver gallium sulfide single crystals

The temperature oscillation method was used to synthesize dense single-phase polycrystalline AgGaS₂ from high purity elements. AgGaS₂ single crystal of 8 mm diameter and 45 mm length, free of voids and crack was obtained by the descending ampoule with steady ampoule rotation method using the synthesized polycrystalline charge. The grown crystal was subjected to powder X-ray diffraction and single crystal X-ray diffraction. The AgGaS₂ has been studied using differential scanning calorimetry (DSC) technique. The single crystal has high transmission of 75% in the Mid IR region. The band gap energy was calculated using absorption spectrum. The stoichiometric composition of AgGaS₂ was measured using energy dispersive spectrometry (EDAX). The structural and compositional uniformities of AgGaS₂ were studied using micro-Raman scattering spectroscopy at room temperature. The photoluminescence behavior of AgGaS₂ has been analyzed. It shows the maximum emission at 538 nm. The resistivity of the grown single crystal has been measured.     

Synthesis,growth and characterization of AgInSe2 single crystals

Single crystal of the ternary semi-conductor AgInSe₂ has been grown by Bridgman technique. The AgInSe₂ crystal crystallizes in the tetragonal chalcopyrite structure. Using melt temperature oscillation method polycrystalline charge was synthesized. The synthesized charge was subjected to powder X-ray diffraction analysis. Thermal property of AgInSe₂ was analyzed using differential scanning calorimetry (DSC) technique. The melting and solidification temperature is 777 °C and 761 °C respectively. The synthesized polycrystalline charge was employed to grow AgInSe₂ single crystals. The grown crystal was confirmed by single crystal X-ray diffraction. The crystal exhibits 60% transmission in the Infrared region. The stoichiometric composition of AgInSe₂ was confirmed by Energy dispersive X-ray analysis (EDAX). The electrical properties of the crystal were studied by Hall Effect measurements and photoconductivity.     

PBN坩埚生长碲锌镉单晶的性能与缺陷研究

采用垂直布里奇曼法,利用热解氮化硼(PBN)坩埚生长碲锌镉单晶(CdZnTe),并对晶体进行定向、切割与磨抛制成(111)面碲锌镉晶片。采用傅里叶红外透过光谱仪、红外透射显微镜、金相显微镜、X射线形貌仪、X射线衍射仪和X射线双晶衍射仪等仪器系统地检测和研究了碲锌镉晶体的性能与缺陷。研究发现:相比于石英坩埚,采用PBN坩埚生长的碲锌镉晶体单晶率和出片率均大幅增加,孪晶、小角晶界和位错密度明显减少。     

Influence of substoichiometry,hydrogen content and crystallinity on the optical and electrical properties of HxWOy thin films

We have prepared H_xWO_y amorphous thin films both by evaporation of tungsten trioxide powder and by cathodic sputtering of a tungsten target in an argon/oxygen/hydrogen reactive gas mixture. The evaporated layers have the composition H_xWO_2.7 (0.2 < × < 0.5). Their oxygen content seems rather insensitive to the evaporation parameters. We do not observe any correlation between x and these parameters. Evaporated virgin layers are nearly transparent. Annealing,under vacuum leaves y unchanged, under oxygen increases y to 3. Annealing of the virgin layer under vacuum induces the growth of the 1.38 eV absorption band (giving blue coloration) and a decrease of the activation energy for conduction. Annealing the blue layers in oxygen destroys the 1.38 eV band and increases the activation energy for conduction. In both cases annealing at high temperature induces a microcrystalline phase with an absorption band centered about 0.72 eV (giving also a blue coloration) and a jump in electronic conductivity. As in the case of the 1.38 eV band, an increase of the intensity of the 0.72 eV band induces a decrease of the activation energy for conduction. The two bands are interpreted as polaronic like. They can be induced in transparent layers without any change in global composition by excitation of the hydrogen atoms from a “ passive” state to an “ active” state. In addition to the hydrogen content, the existence of the 1.38 eV band requires some substoichiometry. The study of the optical and electrical properties of amorphous H_xWO_y sputtered layers, supports our previous conclusions about the composition range (C) for the coloration capability of transparent thin films. In addition there is a composition range (B) where the virgin layers are blue, and a composition range (M) where they have a metallic like behavior. On the other side of (C), there is a range (C’) where uv illumination only induces a decrease in the activation energy for conduction, then a range (T) where the layers are completely nonresponsive. One can pass from (T) to (B) through (C') and (C) either at constant hydrogen content by increasing the departure from stochiometry, or at constant substoichiometry by increasing the hydrogen content. A part of this work was presented at EMC Cornell, New York July 1, 1977.     

Temperature,thickness, and interfacial composition effects on the absorption properties of (Hg,Cd)Te epilayers grown by liquid-phase epitaxy on CdZnTe

Transmission spectra of liquid-phase epitaxy (LPE) Hg_1-xCd_xTe with Cd mole fractions in the range of 0.23<x<0.30 have been obtained as a function of temperature and thickness. The results are described using a model consisting of exponential (Urbach) absorption in the band tail region and band-to-band absorption, predicted by a Kane k p model, for the above band gap region. Modifications to the Urbach and transmission expressions are found to be necessary to properly describe the shape, temperature, and thickness dependence of the spectra. A known composition gradient was found to be sufficient to describe the spectra obtained for thin (<20-μm) samples.