Single crystal growth and physical properties of the Cu2CdGeS4 compound

Single-crystal growth of Cu2CdGeS4

“…It belongs to diamond-like normal-valence semiconductor compounds, which have an average concentration of valent electrons equal to 4 el/ atom. Cu 2 CdGeS 4 has a band gap of 2.05 eV at 290 K and exhibits a p-type conductivity [2]. The measured value of thermo-electric power was as high as 2000 mV/K, which, in combination with the low heat conductivity, indicates possible application as a thermoelement [3].…”

“…Since Cu 2 CdGeS 4 melts incongruently at 1282 K [4], the growth of single crystals was possible using chemical vapour reactions (CVT) method [2,5,6] or gradient freezing from the respective melt [2,6]. Mainly, needle crystals were grown by CVT whereas cleavable single-crystal blocks up to 30 Â 4 Â 5 mm 3 could be obtained by horizontal gradient freezing.…”

“…Mainly, needle crystals were grown by CVT whereas cleavable single-crystal blocks up to 30 Â 4 Â 5 mm 3 could be obtained by horizontal gradient freezing. An attempt to grow larger crystals using a vertical Bridgman method from the field of primary crystallization failed because of the cracking of growth ampoule during the cooling process [2]. That phenomenon was assigned to the negative thermal expansion coefficient of Cu 2 CdGeS 4 , parallel to the b-axis.…”

The reciprocal system Cu2GeS3+3CdSe⇔Cu2GeSe3+3CdS

“…The bandgap energy of Cu 2 CdGeS 4 equals 2.05 eV at 290 K, and the conductivity is ptype (hole) [13]. The thermo-EMF coefficient value is 1800 V/K which, together with low thermal conductivity, indicates a promising material for thermoelectronics [4].…”

Quasi-ternary system Cu2GeS3–Cu2SnS3–CdS

“…The bandgap energy of Cu 2 CdGeS 4 equals 2.05 eV at 290 K, with the hole conduction [9]. The thermo-EMF coefficient reaches 1800 V/K; combined with low thermal conductivity, the compound may be promising for thermoelectronic applications [2].…”