Influence of Mn doping on CuGaS2 single crystals grown by CVT method and their characterization

Abstract

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.