Influence of the growth method on the photoluminescence spectra and electronic properties of CuInS2 single crystals

Abstract

A comparative analysis of free and bound excitons in the photoluminescence (PL) spectra of CuInS2 single crystals grown by the traveling heater (THM) and the chemical vapor transport (CVT) methods is presented. The values of the binding energy of the A free exciton (18.5 and 19.7 meV), determined by measurements of the spectral positions of the ground and excited states, allowed the Bohr radii (3.8 and 3.7 nm), bandgaps (1.5536 and 1.5548 eV) and dielectric constants (10.2 and 9.9) to be calculated for CuInS2 crystals grown by THM and CVT, respectively.

Optoelectronic Properties of Ternary I–III–VI2 Semiconductor Nanocrystals: Bright Prospects with Elusive Origins

“…45 The line width of the free-exciton emission is strongly temperature-dependent, being essentially constant up to 40 K (2 meV), and then increasing to 7 meV at 78 K, 26 meV at 160 K, and 60 meV at room temperature. 34,43,45 Moreover, the emission intensity is strongly reduced upon increasing the temperature (3 orders of magnitude from 4.2 to 120 K), but its spectral position hardly changes with temperature, 34,43,45 because of the very weak temperature dependence of the band gap of CuInS 2 , as discussed above. 40 Besides the free-exciton emission line, the near band-edge emission region (1.50–1.54 eV, inset in Figure 3) also shows another 4 sharp lines at slightly lower energies, which were ascribed to bound-exciton emission.…”

“…The emission of bulk CuInS 2 single crystals was studied in detail in the 1980s by several groups, most notably by Bloem and co-workers (Figure 3) 34,43 and has also been recently revisited by Mudryi et al using higher-quality single crystals, which allowed investigation up to room temperature, while corroborating the essential findings reported in the earlier works. 45 The free-exciton emission line is observed at 1.535 eV at 4.2 K, with a fwhm of 1.6 meV. 34,43,45 The exciton binding energy depends slightly on the composition: 18.5 meV for In-rich and 19.7 meV for stoichiometric CuInS 2 .…”

“…45 The free-exciton emission line is observed at 1.535 eV at 4.2 K, with a fwhm of 1.6 meV. 34,43,45 The exciton binding energy depends slightly on the composition: 18.5 meV for In-rich and 19.7 meV for stoichiometric CuInS 2 . 45 The line width of the free-exciton emission is strongly temperature-dependent, being essentially constant up to 40 K (2 meV), and then increasing to 7 meV at 78 K, 26 meV at 160 K, and 60 meV at room temperature.…”

“…34,43,45 The exciton binding energy depends slightly on the composition: 18.5 meV for In-rich and 19.7 meV for stoichiometric CuInS 2 . 45 The line width of the free-exciton emission is strongly temperature-dependent, being essentially constant up to 40 K (2 meV), and then increasing to 7 meV at 78 K, 26 meV at 160 K, and 60 meV at room temperature. 34,43,45 Moreover, the emission intensity is strongly reduced upon increasing the temperature (3 orders of magnitude from 4.2 to 120 K), but its spectral position hardly changes with temperature, 34,43,45 because of the very weak temperature dependence of the band gap of CuInS 2 , as discussed above.…”

Characterization and photoelectrochemical properties of CICS thin films grown via an electrodeposition route

“…where C sc denotes the space charge capacitance of the depletion region in F cm À2 , q the electron charge in C, 3 0 the vacuum permittivity (8.8 Â 10 À14 F cm À1 ), 3 r ¼ 10 the semiconductor dielectric constant, 42,43 V the applied bias voltage, k B the Boltzmann constant (1.38 Â 10 À23 m 2 kg s À2 K À1 ), T the absolute temperature in K, N the majority charge density of donors or acceptors in the semiconductor (cm À3 ), and A is the electrode surface area in contact with the electrolyte ($1 cm 2 ). V  is the at band potential of the semiconductor, which reects the Fermi level of semiconductor (V).…”