Optical properties of single-crystalline chalcopyrite semiconductor AgInSe2

Abstract

The optical properties of single-crystalline AgInSe 2 have been studied by optical absorption, spectroscopic ellipsometry ͑SE͒, and photoreflectance ͑PR͒ spectroscopy. Optical absorption measurements suggest that AgInSe 2 is a direct-gap semiconductor having an optical band gap of E 0 ϳ 1.2 eV at T = 15-300 K. The pseudodielectric-function spectra, ͑E͒ = 1 ͑E͒ + i 2 ͑E͒, of AgInSe 2 are determined by SE for light polarization perpendicular ͑E Ќ c͒ and parallel to the c axis ͑E ʈ c͒ in the E = 1.2-5.3 eV spectral region at room temperature. The measured SE spectra reveal distinct structures at energies of the critical points ͑E n with n =0-8͒ in the Brillouin zone. The temperature-dependent PR spectra are obtained at T = 15-300 K in the 1.2-1.7 eV spectral ranges. The lowest band-gap energy E 0 of AgInSe 2 shows unusual temperature dependence at T Յ 120 K. The resultant temperature coefficients dE 0 / dT are positive at T Յ 120 K and negative above 120 K, and are explained by considering the effects of thermal expansion and electron-phonon interaction. The spin-orbit and crystal-field splitting parameters are also determined to be ⌬ so = 321 meV and ⌬ cr = −172 meV, respectively, and are discussed from an aspect of the electronic energy-band structure consequences.

Significant Improvement in Thermoelectric Performance of AgInSe2-Based Composites through In Situ Formation of Ag2Se

“…However, it is very difficult to unravel its nature at the moment, and a detailed investigation and analysis are therefore necessary. Besides, the η value of the pristine AgInSe 2 varies from 0.9471 to 0.9650 in the present materials, within the reported values 0.9195–0.9800. ,,− …”

Intrinsically High Thermoelectric Performance in AgInSe2 n‐Type Diamond‐Like Compounds

“…AgInSe 2 is a semiconductor with the band gap of ≈1.19 eV, [31] which has been extensively investigated for solar energy applications, optoelectronic applications, as well as photoelectrochemical applications. [32,33] It possesses a typical tetragonal chalcopyrite structure with the space group I-42d, which is derived from the sphalerite structure with Ag/In orderly replacing Zn. [31] The powder X-ray diffraction (XRD) patterns of AgInSe 2 are shown in Figure S1 (Supporting Information).…”

Cu2SixSn1−xS3Thin Films Prepared by Reactive Magnetron Sputtering For Low-Cost Thin Film Solar Cells

“…The optical energy gap (𝐸 g ) is determined by the extrapolation method. [14] The obtained value is 1.17±0.01 eV, which is between those of Cu 2 SnS 3 (𝐸 g = 0.9 eV) [2] and Cu 2 SiS 3 (𝐸 g = 2.5 eV). [15] The acquired value is close to the bandgap value of single crystal Cu 2 Si 0.39 Sn 0.61 S 3 (𝐸 g = 1.25 eV).…”