间接耦合光探测器分析

分析了有关间接耦合光探测器的论述中对耦合系数的两种不同定义的物理意义，指出其中存在的问题。分析了间接耦合光探测器的实验数据与产品性能，提出结果上的商榷意见。     

Relaxation of photoexcited silver chloride

Relocalization of excess carriers from shallow levels to deep levels is observed in addition to carrier recombination during thermal relaxation of photoexcited silver chloride. Experimental dependences of the parameters of the photostimulated luminescence flash (released light sum and kinetic coefficient) on the relaxation time and temperature are explained within a three-level model including a recombination (luminescence) level, a deep level with energy ΔE ≈ 1.8 eV, and a shallow level with energy ΔE ≈ 0.03 eV with respect to the conduction-band bottom. It was shown that Ag⁺ ion adsorption caused a decrease in the relocalization activation energy from 0.17 to 0.03 eV, which is attributed to the surface nature of the centers responsible for the initial relaxation stage.     

Photoelectric properties of bi-alkali antimonide photocathodes

In this paper, the properties of alkali metals (Li, Na, K, Rb, Cs) are discussed. Due to the fact that the properties of photocathodes are dependent on that of alkali metals, a photocathode of proper chemical composition can be chosen for a special application from the physical and chemical properties of alkali metals which are given.     

Photoelectric properties of MISM phthalocyanine structure

Langmuir-Blodgett films have been prepared from copper tetra-4-t-butylphthalocyanine. A voltage dependence of capacitance can be attributed to the presence of a Schottky depletion layer. The barrier potential was determined as l·4eV, and the carrier concentration about 10²⁴m^?3     

Photoelectric properties of porous and single-crystal silicon heterocontacts

The polarization photosensitivity of a heterocontact of porous and single-crystal silicon is experimentally investigated. A maximum in the photosensitivity is observed at ∼1 mA/W at energies in the range 1.2–2.3 eV, when linearly polarized light is obliquely incident on the surface of the porous-silicon layer. The photopleochroism of these heterostructures depends on the angle of incidence θ, varies roughly as ∼θ², and reaches the maximum value of ∼32% at θ⋍80°. Oscillations due to interference of natural and linearly polarized light in the porous-silicon layers are observed in the photocurrent and the photopleochroism of these structures. Heterostructures consisting of a layer of porous silicon on a silicon single crystal can find application as photoconverters of natural and linearly polarized light. Fiz. Tekh. Poluprovodn. 31, 309–312 (February 1997)     

Photoelectric properties of GaN/GaP heterostructures

Thin interference layers of n-GaN were grown on n-and p-type GaP substrates with (100) and (111) orientations by vapor phase epitaxy in an open chloride system. Photosensitivity spectra of isotypic and anisotypic heterojunctions under linear polarized light from the side of the wideband component (GaN) at oblique incidence were investigated. Induced polarized photosensitivity was observed, and peculiarities of this photosensitivity caused by interference in the GaN layers are discussed. Fiz. Tekh. Poluprovodn. 32, 1206–1210 (October 1998)     

Photoelectric properties of n-CdS/p-InP heterojunctions

The polarization method for studying photoactive absorption is used to investigate the photoconversion processes in CdS/InP heterojunctions as a function of the orientation of the indium phosphide substrate. The results of these investigations demonstrate the sensitivity of the photoelectric processes to several factors, including the crystallographic orientation of the p-type InP substrate and the optical quality of the CdS layer. The induced photopleochroism coefficient of these heterojunctions increases proportionally to the square of the angle of incidence (P _I ∼Θ²). Such CdS/InP heterojunctions can be employed as polarization-photosensitive devices. Fiz. Tekh. Poluprovodn. 32, 72–77 (January 1998)     

The growth and properties of luminescent films on silicon

Luminescent films on silicon might be used to make monolithic display devices if they could be prepared with suitable properties. Thin films of zinc orthosilicate have been grown on single crystal silicon by the chemical reaction between a thermal oxide and a thin layer of zinc fluoride. Such films, activated with manganese, show the bright green cathodoluminescence of the phosphor willemite. The technique used is not critical and the films are uniform, stable and strongly adherent to the silicon. The electrical properties of the films have been investigated and compared with those of adjacent MOS structures by measuring capacitance-voltage characteristics. These show the presence of mobile positive ions in willemite. The current-voltage characteristics are very variable but some samples show a rapid increase in current with positive voltage applied to the metal accompanied by extremely weak green electroluminescence. The light output would need to be greatly increased before the electroluminescence of these films could be used for display devices.     

Photoelectric properties of porous GaN/SiC heterostructures

The origin of photoconductivity in porous structures formed by anodization of GaN/SiC heterostructures has been studied. It is shown by comparing the photoelectric, optical, electrical, and structural properties of untreated and anodized heterostructures that this effect is due to the presence of charged states at the interface between GaN and SiC that are specific to the anodization conditions.     

Photoelectric properties of heterojunctions between silicon and polyhomoconjugated organometallic compounds

Rectifying photosensitive heterojunctions were obtained for the first time by depositing films of polyhomoconjugated organometallic compounds onto Si waters. The photoelectric properties of the obtained structures were studied, and the basic photoelectric parameters of these structures were determined. The new heterojunctions are shown to be promising candidates for developing natural-radiation photoconverters.     

硅酸盐橙色荧光粉的发光性能研究

采用高温固相反应法制备了高效橙色荧光粉Sr3-xSiOs:xEu2+.通过X射线粉末衍射仪(XRD)、扫描电镜( SEM)及荧光分光光度计研究了Eu2+含量和不同助熔剂对荧光粉发光性能的影响,并分析了所制荧光粉的封装性能.研究表明,荧光粉Sr3-xSiO5:xEu2+的晶体结构属正方晶系.当Eu2+的摩尔分数为4％,并用质量分数为3％的NH4Cl作助熔剂时,制得的Sr3-xSiO5:xEu2+的发射光谱强度最大.荧光粉封装后可以有效降低白光LED的色温并提高其显色指数,这表明该荧光粉是一种适用于白光LED的光转化材料.     

导电银浆的制备和性能研究

采用商用微米银片为导电相,玻璃粉为粘结剂,乙基纤维素、松油醇和曲拉通为有机载体制备了烧渗型银浆。利用扫描电子显微镜、方阻仪和百格测试法对烧结银浆的显微结构、导电性和附着力进行表征和研究。实验结果表明:烧结温度、玻璃粉含量和导电相的性质对银浆烧结后的显微结构、导电性和附着力均有较大影响。其中,烧结温度不仅对玻璃粉的熔化情况有影响,而且对烧结后的银浆中银片间的接触程度和与基材的润湿性等也有影响;玻璃粉的含量是影响烧结银浆的导电性和附着力的主要因素;微米银片中掺杂纳米银会导致烧结体中导电颗粒间的致密性下降,进而导致烧结后的银浆的导电性和附着力均下降。     

Effect of iodine impurity on relaxation of photoexcited silver chloride

The time and temperature dependences of relaxation of excited AgCl and AgCl:I crystals is studied by the method of photostimulated flash of luminescence. The presence of iodine impurity in silver chloride gives rise to hole recombination (luminescence) centers and hole traps in the band gap. It is shown that the main contribution to the decrease in the concentration of electrons localized at deep traps is made by the recombination of electrons with holes released thermally from shallow localization levels (iodine-related centers). Estimation of activation energy for the relaxation process showed that these energies for the AgCl and AgCl:I samples under study are the same within the experimental error and are equal to E _{rel 1} = 0.01 ± 0.0005 eV for the initial stage of relaxation and E _{rel 2} = 0.09 ± 0.005 eV for the final state. This fact indicates that the majority of hole traps involved in the relaxation process in AgCl are related to iodine impurity. In the course of thermal relaxation in AgCl, relocalization of nonequilibrium charge carriers from shallow levels to deep levels is observed. The depth of the corresponding trap is E _arl = 0.174 ± 0.03 eV.     

Photoelectric properties of ZnO/CuPc/Si structures

n-ZnO:Al/CuPc/n(p)-Si structures were formed using vacuum-evaporation deposition of copper phthalocyanine (CuPc) layers on the surface of n-and p-Si wafers with subsequent magnetron-sputtering deposition of ZnO:Al layers on the CuPc surface. It is shown that the structures obtained exhibit a high photosensitivity (～80 V/W at T=300 K) in the spectral range 1.65–3.3 eV. The rectification factor and photovoltaic effect in these structures are discussed in relation to the properties of silicon substrates. It is concluded that the contact of phthalocyanine with diamond-like semiconductors (e.g., silicon) are promising for application in wide-band high-efficiency photovoltaic converters.     

n-ZnO/p-GaN异质结紫外探测器及其光电性能研究

利用脉冲激光沉积(PLD)方法在p-GaN衬底上沉积了n-ZnO薄膜,构造了n-ZnO/p-GaN异质结型紫外(UV)光-电探测器原型器件,在(UV)光照条件下测试了器件的光电性能。扫描电镜(SEM)和X射线衍射(XRD)测试结果表明,ZnO薄膜具有很好的结晶质量;I-V曲线显示,器件在黑暗和光照环境下都表现出明显的整流行为;光谱响应曲线表明,器件响应度峰值出现在364nm附近,当反向电压为-5V时光电流达到饱和,此时响应度峰值达到1.19A/W。不同反向工作电压下的光谱探测率曲线表明,器件对364nm附近的UV光有较强的选择性,在-2V偏压下具有最佳的探测率,其探测率峰值达到8.9×1010 cm·Hz1/2/W。     

碳化硅材料发光特性研究进展

碳化硅作为一种优秀的微电子材料,在高频、高温、大功率、强辐射环境中颇具应用潜力。然而由于其间接带隙的特点,碳化硅LED不能像氮化镓、磷化镓LED那样有效发光,因此人们竞相研究能提高碳化硅发光效率的方法,其中包括非晶碳化硅、多孔单晶碳化硅、用CVD方法制备的纳米碳化硅和用离子注入方法制备的多孔碳化硅。在最近几年,这些研究已取得巨大进展,从而使其成为适用于发展中的OEIC技术的颇具潜力的材料。     

Synthesis of silver nanoparticles and the optical properties

Silver nanoparticles (NPs) of 5-15 nm are synthesized with the reduction of silver nitrate (AgNO3 ) by formaldehyde (HCHO) and using polyethylenemine (PEI) as a stabilizer. Transmission electron microscopy (TEM) analysis shows the size of the Ag NPs increases with the increase of HCHO contents. The absorption and emission peaks of the original colloids are red shifted with increasing the size of Ag NPs. The absorption and emission peaks are at 344 nm, 349 nm, 357 nm, 362 nm, 364 nm and 444 nm, 458 nm, 519 nm, 534 nm, 550 nm, respectively. The fluorescence intensities of the silver colloids increase with increasing the NPs size (or the contents of HCHO). With the diluted fold increasing, the fluorescence intensity of the diluted silver colloids increases firstly then decreases. Compared with that of the original silver colloids, the emission peaks are blue shifted. For the diluted silver colloids, when the fluorescence intensity is maximum, the emission peaks are all near 444 nm. The 16-fold diluted silver colloid gets to the maximum emission intensity when the mole ratio of AgNO3 and HCHO is 1:6.     

Photoelectric properties of GaAs/InAs heterostructures with quantum dots

The capacitive photovoltage and photoconductivity spectra of GaAs/InAs heterostructures with quantum dots is discussed. For these structures, which were fabricated by metallorganic gas-phase epitaxy, the photosensitivity spectrum has a sawtoothed shape in the wavelength range where absorption by the quantum dots takes place, which is characteristic of a δ-function-like density of states function. The spectra also exhibit photosensitivity bands associated with the formation of single-layer InAs quantum wells in the structure. An expression is obtained for the absorption coefficient of an ensemble of quantum dots with a prespecified size distribution. It is shown that the energy distribution of the joint density of states, the surface density of quantum dots, and the effective cross section for trapping a photon can all be determined by analyzing the photosensitivity spectrum based on this assumption. Fiz. Tekh. Poluprovodn. 31, 1100–1105 (September 1997)     

无颗粒银导电墨水及高导电率银薄膜的制备及其性能研究

以酒石酸银为原料、1,2丙二胺为络合剂、无水乙醇为溶剂制备了无颗粒银基导电墨水,将该墨水棒涂于玻璃、PET、PI和相纸基板,在加热板上130℃固化5 min获得银膜,通过XRD、FTIR、TG-DSC、FE-SEM和四探针测电阻率方法对合成的酒石酸银粉体、导电墨水和银膜进行表征。结果表明:导电墨水的分解温度远低于银前驱体的分解温度;在不同基板上的银薄膜表现出不同的形貌和颗粒尺寸,其中相纸基板上的电阻率最低为6.7×10~(–6)?·cm。喷墨打印银线条于PI基板,130℃固化5 min后,银线条宽度约100μm,表面平整光滑且微观组织致密,在柔性印刷方向有良好的应用前景。     

Photoelectric properties of ZnO films doped with Cu and Ag acceptor impurities

The influence exerted by doping with Cu and Ag acceptor impurities at a content of 1, 3, and 5 at. % on the luminescence and photoconductivity of zinc oxide films has been studied. Electron-beam evaporation in optimal modes has been used to obtain films with predominant luminescence in the UV spectral range. It has been shown that the incorporation of copper yields three types of point defects in ZnO: Cu_Zn (3d¹⁰), Cu_Zn (3d⁹), and Cu_i; and in silver, a single type: Ag_Zn (3d¹⁰). Precipitation of a silver oxide phase at the highest impurity concentration has been observed. Impurity incorporation leads to a pronounced increase in the resistance and photosensitivity of films.