Electrical and Optical Properties of CuInSe_2 Grown by Traveling Heater Method Using Pure In and Cu-In Alloy Solvents

摘要

The ternary compound semiconductor crystals of CuInSe_2 were grown by the traveling heater method using pure In or Cu-40 at% In alloy as the solvent. The EPMA composition mapping was stoichiometric and homogeneous throughout the crystals. By using pure In and Cu-In alloy solvents, the n- and p-type conductions resulted, respectively. The carrier concentration and the Hall mobility at 300 K were 4 x 10~(22) ～ 1 x 10~(23) m~(-3) and 3 x 10~(-2) ～ 9 x 10~(-2) m~2 V~(-1)s~(-1) for n-type and in the order of magnitude of 10~(21) m~(-3) and 10~(-3) m~2 V~(-1)s~(-1) for p-type, respectively. The photoluminescence spectra indicated the characteristic features depending upon the solvents. In the case of n-type, the emission origins in the n-type crystal were identified as free exciton and V_(Se), while those in the case of p-type were free exciton, Cu_(In) and V_(Se). The emission intensity measurements indicated that the excitonic emission was predominant in the crystals grown by THM and increased from bottom to top end in the crystals, where lattice defects remained almost constant. The results for the crystals grown by THM showed a clear contrast to that obtained from that by the Bridgman method in which the non-radiative recombination centers were predominant. The laser Raman spectra were almost similar among the CuInSe_2 bulk crystals grown by THM and the Bridgman method.