1 and 2 mole% of Mn doped CuGaS2 (CGS) single
crystals were grown by the chemical vapour transport (CVT) technique using
iodine as the transporting agent. The analysis of the single crystal x-ray
diffraction data suggests that the doping of 1 and 2 mole% Mn in the CGS single
crystal does not affect the tetragonal (chalcopyrite) crystal structure. The
optical absorption spectrum shows that the Mn ion induces a very strong
absorption band in the UV–visible–near IR regions. The values of the crystal
parameter (Dq) and the Racah parameter (B) calculated from the absorption
spectra show d electron delocalization in the host crystal CGS. Room
temperature photoluminescence spectra of undoped CGS only exhibited a band–band
emission. But 1 and 2 mole% Mn doped CGS single crystals show two distinct CGS
and Mn2+ related emissions, both of which are excited via the CGS host lattice.
Raman spectra of 1 and 2 mole% Mn doped CGS single crystals exhibit a high
intensity peak of the A1 mode at 310 cm−1 and 300 cm−1, respectively. EDAX,
optical absorption and Raman spectrum studies reveal that Mn2+ ions are
substituted in the Ga3+ ions and incorporated into the CGS lattice. The
magnetization of Mn doped CGS single crystals was measured as a function of the
magnetic field and temperature. Paramagnetic behaviour typical of spin S = 5/2
expected for Mn2+ (d5) magnetic centres was observed in the temperature range
2 K < T < 300 K. In Mn doping, the increase in bulk conductivity of the
Mn doped CGS single crystals at room temperature indicates an increase in the
hole concentration.
Source:IOPscience
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