Selenium Vapor Pressure Research Articles

Preparation and some semiconducting properties of CuInSe 2 thin films

Thin films of CuInSe 2 were prepared by d.c. sputtering and vacuum evaporation from the synthesized bulk material. It is usual for p-type films to be obtained by d.c. sputtering. Both p- and n-type vacuum-evaporated films are obtained by controlling selenium vapor pressure or substrate temperature. The vacuum-evaporated films show a fundamental absorption similar to that of the bulk crystals. The obvious shift of the fundamental absorption edge is observed for p-type evaporated films depending upon the hole concentrations. Photoconductivities are observed for the n-type evaporated films. Some samples show high photoresponse beyond the fundamental absorption edge.

Photoconductivity and extrinsic doping of pCuInSe 2

Diffusion experiments under maximum selenium vapor pressure have been carried out on monocrystalline p-type CuInSe 2 samples. Change of resistivity after the treatments at different temperatures was investigated. Diffusion experiments were also made under bismuth and tellurium dopant atmosphere. It was found that n-type samples resulted after the bismuth diffusion, and the samples remained p-type after the tellurium diffusion. For bismuth diffusion experiments, it is believed that selenium out-diffusion is dominant during the process. Photoconductivity experiments of p-type monocrystalline CuInSe 2 samples were also performed at 77 K in the wavelength range from 0.4 to 1.6 μm. Deep etching treatment of the sample appeared to reduce the surface recombination velocity.

Phase equilibrium of the VSe 2/1bV 3Se 4 system and the thermodynamic quantities of the V 3Se 4 phase

The equilibrium selenium vapour pressure of V xSe 2 (1.2 < x < 1.7) was measured by a thermobalance method at 1053, 1113 and 1163K under controlled selenium vapour pressure. The thermodynamic partial molar quantities of the V 3Se 4 phase were evaluated from the measured P Se- X isotherms. Further, the powder X-ray and high temperature DTA measurements of the quenched specimens were carried out in order to identify the phase.

Defect Structure of Cu-Doped Cadmium Selenide

High-temperature conductivity and copper solubility in CdSe is measured over the range 600 to 900°C as a function of temperature and cadmium and selenium vapour pressure. It is found that in cadmium vapour (pCd > 10−1 atm) below 750°C the main part of copper is in electrically inactive form and with increasing temperature transfers to the electrically active interstitial form Cu The activation energy of transference is found to be (2.0 ± 0.28) eV. In cadmium vapour the incorporation of copper occurs by the mechanism of controlled electronic imperfections with the electroneutrality condition (ENC) n = Cui and in selenium vapour by the mechanism of controlled atomic imperfections with ENC Cu = (CuVCd)′. [Russian Text Ignored].

Growth of single crystals of V xSe 2 by chemical transport with iodine

The chemical transport of V x Se 2 was carried out using iodine as a transport agent. The selenium vapour pressure was uniform throughout the tube and was the same as the equilibrium pressure of the starting material. The transport gas was identified as VI 4 by in situ observation using spectrophotometry. Transport took place according to the reaction VSe 2(s) + 2I 2(g) ⇌ VI 4(g) + Se 2(g)

The solid state controlled growth of sulphides and selenides of Ag and Cu using crystal rotation

An improved crystal growth method for ionic-electronic mixed conductors, such as the high temperature cubic modifications of Ag 2X and Cu 2X (where X = S or Se), is presented. Ag or Cu atoms are mobile in these compounds. If the respective sulphur or selenium vapour pressure was sufficiently high at the growth surface, the growth rate was limited by the solid state chemical diffusion of Ag or Cu atoms which was controlled by the rate of the injection of the metal atoms into the compounds. The crystals were grown in a silica ampoule, held in a vertical two zone furnace and rotated at 1 rpm about the vertical axis to achieve a uniform axial temperature distribution. Nearly cylindrical single crystals of size about 3–10 mm diameter, 10–35 mm long were grown by this method.

非化学量論化合物NbSe&lt;I&gt;&lt;SUB&gt;x&lt;/SUB&gt;&lt;/I&gt; (&lt;I&gt;x&lt;/I&gt;=1.48&amp;sim;2.00)の熱力学的性質と結晶構造

The pressure-composition-temperature relations for niobium selenides NbSex were determined by annealing under controlled selenium vapor pressure in the composition range x=1.48∼2.00. Five phases were confirmed. Single crystals of these phases were grown by the chemical transport method, and their structures were determined by X-ray diffraction. Their ranges of stability are:(1) Hexagonal 4 H phase: above 5 Torr Se2 partial pressure at 900°C for x=2.00.(2) The phase below 5 Torr Se2 partial pressure for x=1.99∼2.00 is a 2 H structure but probably different from 2 H (b) structure proposed by F. Jellinek, designated as 2 H (β).(3) Rhombohedral 3 R phase: 1.80<x<1.86 at 1000°C and 1.79<x<1.91 at 900°C.(4) Hexagonal 2 H (a) phase: 1.68<x<1.82 at 1100°C and 1.66<x<1.76 at 1000°C.(5) Monoclinic Nb2Se3 phase: 1.48<x<1.52 at 1100°C and 1000°C.Within the stability range of the 3 R and 2 H (a) phases, the composition varies with Se2 pressure. These variations can be explained on statistical thermodynamic grounds by assuming that excess Nb atoms randomly occupy the octahedral interstitial sites of a stoichiometric NbSe2 structure.

High-temperature conductivity of undoped and Copper-doped cadmium selenide

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The Role of Selenium Vapor Pressure in the Formation of Silver Doped Manganese Selenide

The effect of selenium vapor pressure on containing small additions of has been studied by both weighing and electrical measurements. Three distinct regions have been noted. At low selenium pressures selenium is taken up by the mixture to form the mixed valence compound . The value of ⊕, the hole concentrations, increases as a function of the selenium pressure until all is used up and the sample becomes a single phase. At this equivalence point the pressure then increases rapidly with little change in composition. Finally, the pressure becomes sufficiently high that manganese vacancies are produced. These regions are described in terms of mass action expressions which link the vapor pressure with vacancies and electrical charge carrier concentrations.