Optical and Electrical Properties of GeSe and SnSe Single Crystals

GeSe and SnSe single crystals were fabricated by using Bridgman technique. The properties of the two crystals were investigated by temperature-dependent Hall effects, optical absorption, and pressure-dependent Raman scattering measurements. The hole carrier concentrations of the GeSe and SnSe samples were 5.31x10(16) cm(-3) and 1.19x10(19) cm(-3), respectively, at room temperature. The activation energy of acceptor levels in GeSe and SnSe were measured to be 37.8 meV and 2.21 meV, respectively. These compounds had indirect band gap, which were measured to be 1.10 eV for GeSe and 0.88 eV for SnSe, respectively. The Raman spectra of GeSe and SnSe were obtained under high pressure up to 5.62 GPa. GeSe showed four major peaks at 89 cm(-1) (A(g) ), 154 cm(-1) (B-3g ), 180 cm(-1) (A(g) ), and 191 cm(-1) (A(g) ), and SnSe had three peaks at 84 cm(-1) (A(g) ), 118 cm(-1) (B-3g ), and 137 cm(-1) (A(g) ). The effects of applying high pressure on these modes were also discussed.