Band‐Edge Electronic Structure of β‐In₂S₃: The Role of s or p Orbitals of Atoms at Different Lattice Positions

Abstract

As a promising solar-energy material, the electronic structure and optical properties of Beta phase indium sulfide (β-In(2)S(3)) are still not thoroughly understood. This paper devotes to solve these issues using density functional theory calculations. β-In(2)S(3) is found to be an indirect band gap semiconductor. The roles of its atoms at different lattice positions are not exactly identical because of the unique crystal structure. Additonally, a significant phenomenon of optical anisotropy was observed near the absorption edge. Owing to the low coordination numbers of the In3 and S2 atoms, the corresponding In3-5s states and S2-3p states are crucial for the composition of the band-edge electronic structure, leading to special optical properties and excellent optoelectronic performances.

Photoexcited Carrier Dynamics of In2S3 Thin Films

“…The TA data reveal an ultrafast decay of conduction band electrons and also experimentally corroborate the existence of a significant secondary conduction band ∼2.1 eV above the main band, as recently predicted by density functional theory calculations. 20 Our results are further consistent with a large density of states below the conduction band, likely due to V S and In i . 10−12 In 2 S 3 thin films were grown by atomic layer deposition (ALD) under ultrapure N 2 using an oxygen-free metal organic precursor.…”

“…The remaining broad photoinduced absorption feature (Figure 4a, dashed red curve) is attributed to electrons photoexcited by the pump that are further excited by the probe pulse into a secondary conduction band ( Figure 5, full red line). 20 As previously discussed, this presence of a large density of states ∼2.1 eV above the CBM has been postulated computationally. 20 The decay of these features with a time constant of ∼25 ps is consistent with assignment of room-temperature PL to band-edge recombination, which decays at a similar rate.…”

“…20 As previously discussed, this presence of a large density of states ∼2.1 eV above the CBM has been postulated computationally. 20 The decay of these features with a time constant of ∼25 ps is consistent with assignment of room-temperature PL to band-edge recombination, which decays at a similar rate. The second, longer-lived component of the TA spectra can be deconvolved into two induced absorptions, both with less intensity and blue-shifted relative to the first positive feature (Figure 4b,d,f, dark-blue and orange dashed curves).…”

Synthesis of In2S3 and In6S7 Microcolumns and Nanowires by a Vapor‐Solid Method

“…Tetragonal β‐In 2 S 3 is the most studied In 2 S 3 phase as it is stable at room temperature. It presents a defective spinel structure with an indirect bandgap of around 2.0 eV, and behaves as an intrinsic n‐type semiconductor due to the presence of S vacancies, with large photoconductivity responses . It also presents a variable direct bandgap of 2.2–2.8 eV, which is strongly dependent on its growth conditions, stoichiometry and microstructure .…”

Sulfurization-induced growth of single-crystalline high-mobility β-In2S3 films on InP

“…12,22 Finally, peak C most likely corresponded to a higher energy state correlated with S 3p and In 5s states, and was also observed for ALD-grown polycrystalline β-In 2 S 3 films. 8,23 Importantly, no mid-gap states (1.5-1.6 eV) corresponding to intrinsic defects were observed. Compared to RT (300 K) spectra, the blue shifts of 39.12 meV (peak A) and 57.01 meV (peak C) at 40 K and narrowed are observed at 407.29 (3.04) and 535.58 nm (2.315 eV), respectively, at LT (40K).…”