Growth and optical properties of solid solution crystals GaSe1−xSx

• GaSe1−xSx crystals were grown.
• 3 weight % of S is optimal.
• Absorption anisotropy decreases with doping.

GaSe1−xSx (x = 0, 0.01, 0.05, 0.13, 0.22, 0.29, 0.44) crystals were grown by modified vertical Bridgman method that provided (0001) crystal plane orientation perpendicular to growth axis. Absorption coefficient is minimal (decreased by up to 3 times) in the THz range at the optimal S-doping of 3 weight % (x = 0.13). Increased S content causes the absorption coefficient for e-wave to become frequency independent in the main part of the spectrum from 0.3 to 3 THz. A narrow line-width rigid phonon absorption peak E″(2) at 1.79 THz arises and then declines in intensity with the doping level, in parallel with a shift towards shorter wavelength.

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