Optical absorption edge and luminescence in phosphorous-implanted Cu6PS5X (X = I, Br) single crystals - I. P. Studenyak; Yu. Izai; V. O. Stephanovich; V. V. Panko; P. Kúš; A. Plecenik; M. Zahoran; J. Gregus; T. Roch (Semiconductor Physics, Quantum Electronics and Optoelectronics, 2011)