Ab initio calculation of high pressure phases and electronic properties of CuInSe2

Phase stability and elastic properties of CuGaSe2 under high pressure

“…The P4/mmm space group obtained from Fm3m that can distinguish Cu and In sites in the primitive cell. These results confirm the experiments and calculations studies [10][11][12], but we can distinguish the Cu and Ga sites in Fm3m and Cmcm to the P4/ mmm and Amm2, respectively. At the transition pressure 52 GPa (P4/mmm to Amm2), the equilibrium point in cubic phase (P4/ mmm) was pressed, and changed to orthorhombic space group (Amm2) as shown in Fig.…”

“…2(c). The Cu-Se planes shift from Ga-Se planes that same as the CIS [11] and CIGS [27] phase transitions. The phonon density of states (PDOS) in I42d (0 GPa), (30 GPa) and Amm2 (80 GPa) were compared in Fig.…”

“…The experiments suggested the atomic positions of cations (I-III) in Fm3m and Cmcm are the same atomic positions. Ab initio calculations [11,12] compared the free energies of space groups (I42d, Fm3m and Cmcm) from the experiments suggestion. The enthalpy comparisons showed that the order of phase transitions both CuInSe 2 and CuGaSe 2 are I42d-Fm3m-Cmcm.…”

Electrical Transport Properties and Band Structure of CuInSe2 under High Pressure

“…As shown in Figure , the resistivity of CuInSe 2 is always kept decreasing with increasing temperature over the entire pressure range, indicating that both tetragonal phase and cubic phase perform a semiconductor behavior. This result is similar to the experimental result of CuFeS 2 and CuInS 2 but inconsistent with the theoretical calculation revealing that CuInSe2 undergoes a metallization phase transition at 15.0 GPa. ,, In addition, it also can be clearly seen from Figure that when the pressure is less than 7.0 GPa the slope of the line used to linearly fit the temperature-varying resistivity increases slowly with the pressure, but when the pressure is greater than 8.6 GPa, the slope turns to decrease with the increase in pressure. In order to obtain the internal conduction mechanism of the carrier, we deduced the activation energy from the variable-temperature resistivity by eq where ρ is the resistivity; ρ 0 is a prefactor; K is Boltzmann constant; E a is the activation energy; and T is the temperature.…”

“…A previous theoretical study has showed that CuAlX 2 (X = S, Se, Te), which are analogues to CuInSe 2 , will change the structure from the tetragonal phase to the cubic phase under high pressure, and a pressure-induced metallization transformation was found accompanied by the transition . Pluengphon et al predicted that the band gap of CuInSe 2 will be close to 15.0 GPa by ab initio calculations, which means that the semiconductor-to-metal transition occurs at the critical pressure . In fact, we still need more direct and effective measurements to prove the metallization of CuInSe 2 under certain pressures.…”