Crystal structure and physical properties of GaSe single crystals annealed in sulfur atmosphere

Abstract

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.

GaSe1−x S x solid solutions

“…Exactly this circumstance limits the energy parameters of laser radiation in the range 0.7-1.3 µm converted into the middle IR and terahertz ranges. In particular, the power of dye laser pulses converted into the middle IR range is limited by a subkilowatt level [1, [3][4][5][6][7][8][9][10][11].…”

“…The GaSe:Er (0.5 mass%) crystals kept their hexagonal structure unchanged and demonstrated a 24% increase in the second-order nonlinear susceptibility coefficient [11]. In turn, doping with sulfur led to a noticeable improvement of all physical properties of the GaSe crystals: improvement of cleavage with the corresponding reduction of the coefficient of linear optical losses in comparison with pure GaSe crystal grown by the available technology, increase in the nonlinear susceptibility coefficient, and shift of the absorption spectrum toward shorter wavelengths [7][8][9][10]. We note that the shift of the absorption spectrum toward shorter wavelengths must result in the corresponding reduction of the nonlinear optical losses.…”