HgGa2Se4 under high pressure: an optical absorption study

High-pressure optical absorption measurements have been performed in defect chalcopyrite HgGa2Se4 to investigate the influence of pressure on the bandgap energy and its relation with the pressure-induced order-disorder processes that occur in this ordered-vacancy compound. Two different experiments have been carried out in which the sample undergoes either a partial or a total pressure-induced disorder process at 15.4 and 30.8GPa, respectively. It has been found that the direct bandgap energies of the recovered samples at 1GPa were around 0.15 and 0.23eV smaller than that of the original sample, respectively, and that both recovered samples have different pressure coefficients of the direct bandgap than the original sample. A comprehensive explanation for these results on the basis of pressure-induced order-disorder processes is provided. This study was supported by the Spanish government MEC under Grants No: MAT2010-21270-C04-01/03/04 and MAT2013-46649-C4-1/2/3-P, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), by Generalitat Valenciana (GVA-ACOMP-2013-1012 and GVA-ACOMP-2014-243), and by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E. P.-G., J. L.-S., P. R.-H, and A. M. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. J.R.-F. thanks the Alexander von Humboldt foundation for a postdoctoral fellowship. Gomis, O.; Vilaplana Cerda, RI.; Manjón Herrera, FJ.; Ruiz-Fuertes, J.; Pérez-González, E.; López-Solano, J.; Bandiello, E... (2015). HgGa2Se4 under high pressure: an optical absorption study. physica status solidi (b). 252(9):2043-2051. https://doi.org/10.1002/pssb.201451714 Bernard, J. E., & Zunger, A. (1988). Ordered-vacancy-compound semiconductors: PseudocubicCdIn2Se4. Physical Review B, 37(12), 6835-6856. doi:10.1103/physrevb.37.6835 Jiang, X., & Lambrecht, W. R. L. (2004). Electronic band structure of ordered vacancy defect chalcopyrite compounds with formulaII−III2−VI4. Physical Review B, 69(3). doi:10.1103/physrevb.69.035201 Burlakov, I. I., Raptis, Y., Ursaki, V. V., Anastassakis, E., & Tiginyanu, I. M. (1997). Order-disorder phase transition in CdAl2S4 under hydrostatic pressure. Solid State Communications, 101(5), 377-381. doi:10.1016/s0038-1098(96)00602-3 Gonz lez, J., Rico, R., Calder n, E., Quintero, M., & Morocoima, M. (1999). Absorption Edge of MnGa2Se4 Single Crystals under Hydrostati