High-pressure x-ray absorption study of InSe

The III-VI layered semiconductor InSe has been studied by high-pressure sin gle crystal x-ray absorption spectroscopy up to a maximum pressure of 14 GP a. The In-Se distance has been measured in both the low-pressure layered ph ase and the high-pressure NaCl phase. The bond compressibility in the layer ed phase is lower than the "a" crystallographic parameter compressibility, which implies an increase of the angle between the In-Se bond and the layer plane. Under plausible hypothesis, a description of the evolution of the w hole structure with pressure is given. In particular, the intralayer distan ce is observed to increase with increasing pressure. A plausible precursor defect and a simple mechanism for the transition are also presented. The co nclusions can be readily translated to other III-VI layered semiconductors. [S0163-1829(99)07729-2].