In_xGa_1−xSe mixed crystals grown from an In flux by the traveling heater method for THz wave generation

The growth rate of crystalline GaSe from solution was increased by using indium as a solvent. The solubility and concentration gradient of Se were measured using differential scanning calorimetry (DSC). The Se solubility and the temperature coefficient of the solubility were respectively 15 times and 2.2 times greater in crystals grown from an In flux with GaSe at saturation compared with the case of Se dissolved in a Ga flux. In this study, we succeeded in growing In_xGa_1−xSe ingots from an In flux without the need for a seed crystal, and in increasing the growth rate of GaSe from solution. In addition, we used difference frequency generation to generate THz waves (with a frequency of 9.7 THz) in an In_xGa_1−xSe mixed crystal and investigated the relationship between the output energy of the THz radiation and the interaction length of the excitation light. The conversion efficiency of THz wave (9.7 THz) from the In_xGa_1−xSe mixed crystal with thickness of 860 μm was 26 times greater than that of GaSe crystal with thickness 100 μm grown from Ga solvent. (paper)