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Real defect structure, growing technology and physical properties of doped GaSe:S crystals are presented. From comparative experiment on CO 2 laser SHG at identical experimental conditions 1.45 times advantages of GaSe:S (2 wt%) in relation to pure and GaSe:In (0.1 wt%) crystals are developed.

Gallium selenide is a material with great potential for nonlinear optical applications, due to its many attractive properties, including a broad low-loss transmittance (from 0.65 to 18 μm) and a large nonlinear coefficient. However, its current application is limited due to difficulties with its growth, and poor mechanical properties. Our current research has a threefold purpose. First, this work is intended to investigate the feasability of growing large, optical quality single crystal boules of GaSe; second, to investigate the impact of isovalent indium doping on the mechanical, electrophysical, and optical properties of GaSe, and third, to determine the concentration of In which is optimal for purposes of facilitating the practical implementation of GaSe in nonlinear devices.

Using thermodynamic calculation, the equilibrium concentrations of point defects in ZnGeP2 and CdGeAs2 depending on a liquidus temperature are obtained. The conclusion about a high degree of compensation of native donors and acceptors is made. The methods of a model pseudo-potential and large unit cell are used for investigation of deep levels created by vacancies and antisites in the forbidden band of ZnGeP2. Optical transitions with participation of the defects are defined. It is supposed the possibility of conditions favourable for mid-IR optical absorption, as a result of the interaction of ionized zinc vacancies with GeP clusters.

Research in doping processes of ternary chalcopyrites A 2 B 4 C 2 5 is of primary interest for several reasons. First of all, a study of the dependencies of ‘the properties of crystal vs. the concentration of impurity in melt’ decides a fundamental problem. It is a check on the theory of ordering of a crystal structure for some specifically defined values of dopant concentration leading to a possible phase transformation caused by the self-organization of large-scale fluctuations in a melt. On the other hand, it is necessary also for practical tasks—for example, obtaining high-resistance CdGeAs 2 -crystals for use in nonlinear optics. In the present work data on electrical activity and on an effect in the electrophysical properties of ternary semiconductors CdGeAs 2 and CdSnAs 2 are obtained for dopants of Au, Cu, Zn, In, Sc and Gd in CdGeAs 2 and for Au, Cu and In in CdSnAs 2 , added to a melt during synthesis or recrystallization of a material.

This paper presents the results of investigation on influence of doping with sulfur and annealing in sulfur atmosphere on properties of promising nonlinear optical gallium selenide crystals, grown by the Bridgeman method from melts with content of sulfur 0.01-3 mass % and annealed in sulfur atmosphere.

The physical properties of pure GaSe and the crystals doped with 0.01÷3% Al, In, Te, and S have been observed comparatively to reveal the potentials for frequency conversion of laser emission. It has been shown that GaSe:S(greater than or equal to 3%) is the most promising material for practical applications.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In spite of the progress in GaSe growing technology (high-quality crystals grown by the latest technology are characterized by low values of optical losses with the absorption coefficient values lying below 0.1 cm−1) the work continues on improving crystal properties for nonlinear optical applications. This paper presents the results of investigations on the influence of annealing in a sulfur atmosphere and in a vacuum on the properties GaSe single crystals, grown by the Bridgman method from the melt. The objective of this work was to study the possibility of intercalating GaSe with sulfur from the gas phase, and to compare the influence of doping with sulfur from melt and vapor phase on the structure and properties of GaSe crystals. Three series of annealing experiments have been conducted at temperatures 773, 923, 1073 K and the samples obtained have been studied by Hall effect, photoconductivity, optical absorption, microhardness measurements and X ray diffractometry. The results obtained are explained by assuming the intercalating of sulfur to the interlayer space and substitution of Se with S.

We present an investigation of the diffusion and melt doping of Cu in CdGeAs2. Cu was found to be an acceptor, its introduction in the melt allowed the controlled introduction of holes from ∼8·1016 cm-3 to ∼1·1018 cm -3. Introduction of Cu from the melt was also found to improve the homogeneity of the crystal. The saturation solubility of Cu introduced via diffusion doping was found to have an exponential dependence on the diffusion temperature, from 723 K to 873 K, obeying the equation N = N0 exp (- δH / kT) with the parameters N0 = 6.10+19 cm-3, δH = 0.3 eV, and k equal to Boltzman's constant. From 873 K to 923 K, the saturation solubility was found to decrease exponentially with temperature.

Absrtact:The attempt to obtain the data on thermodynamic parameters and equilibrium concentra- tions of disorder defects was made. Quasi-chemical model of the defects formation with allow- ance for Schottky and Frenkel defects was used. Thermodynamic parameters were calculated based on Weiser's technique. Six types of the disorder defects in II-IV-V2 and I-III-VI2 were considered. Used models, approaches and initial parameters give that the greatest concentration (∼ 1019 cm−3) and accordingly the greatest influence on properties of the crystals have defects AB or BA.

Experiments on annealing of CdGeAs2-, CdSnAs2- and ZnGeP2-crystals in the vapor of volatile constituents were carried out. Conductivity and Hall effect measurements were performed to characterize the modification of electrical properties, caused by the interaction of the crystal with the gas phase during annealing. Literature data and the results of the present work are discussed based on the results of a quasi-chemical analysis. This yielded that the results of annealing depends essentially on both the conditions of the experiment and the initial imperfection of the crystal. The most probable native structural defects becoming apparent under the annealing were the following: for CdSnAs2 - SnCd, VAs; for CdGeAs2 - VAs, VCd, CdGe, GeCd; for CdSiAs2 - SiAs, VAs ; for CdSiP2 - VCd, VP; for ZnGeP2 - ZnGe, GeZn, VZn, VP; and for ZnSnP2- ZnSn, SnZn, VZn, VP.

The work deals with ternary nonlinear optical crystals of I- III-VI2, and II-IV-V2-type. Theoretical thermodynamic method of quasi-chemical reactions was used. Entropy of vacancy was calculated as sum of configuration and vibration components. For the first one uncertainty in positions of new bonds formed by unpaired electrons arisen when one of consistent atoms is deleted and uncertainty in new positions of relaxing atoms were considered. Standard Boltzmann expression for configuration entropy (Delta) Sconf equals (Sigma) klnw and geometry considerations were used. It was assumed that the vibration component is caused by change in vibration frequency of atoms surrounding formed vacancy. Change in length of bonds and in bonding force took into account. Approximate expression for vibration entropy change (Delta) Svibr equals 3Nkln, geometry considerations and results of bonds lengths calculations were used.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Fourteen A2B4C25- and A1B3C26-compounds with chalcopyrite-type crystal structure are under investigation. The process of formation of a sole ternary compound form chemical elements is dealt with. Design-based model anticipates adiabatic conditions. Characteristics of the self-propagating high-temperature synthesis such as adiabatic combustion temperature, initial temperature of synthesis process, share of liquid phase in combustion product are calculated.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The quantity of material in vapour phase was defined by the weight-loss measurements. Two models of dissociation of CdGeAs2 and CdSnAs2 were considered. The models were based on condition of incongruent evaporation Model 1 and 2 called for absence or existence of Cd3As2 formation in gas phase. Corresponding sets of simultaneous equations were solved. The analyses of the results were carried out. An attempt to estimate the thermodynamic parameters of the compounds and values of total and partial equilibrium pressures at the melting point and lower temperatures was made.