Optical absorption and photoelectric properties of Ga₂In₄S₉ single crystals

Abstract

Presented in this paper are the results obtained from the investigation of absorption edge and photoconductivity of layered Ga,In4S9 single crystals as well as from the investigation of the photovoltaic effect in Pt-Ga21n,Sp surface-barrier structures. We determined the magnitude of the direct band gap to be E, = 2.72 eV and the position of the sensitizing centres to be xO.15 eV above the valence band top. In the regions of the photon energies smaller than E, the absorption band edge is described by an exponential dependence with a temperature independent slope.

Liquid‐Alloy‐Assisted Growth of 2D Ternary Ga2In4S9 toward High‐Performance UV Photodetection

“…In order to obtain more detailed information about the emission properties, temperature‐dependent CL characterization was carried out from 113 to 293 K. As shown in Figure b, the position of the near‐band‐edge emission presents an obvious redshift from 2.81 to 2.78 eV (Figure c) with the increasing of surrounding temperature derived from electron–phonon interaction and lattice thermal dilation, but the intensity changes only slightly. It is worth noting that the change of near‐band‐edge emission with temperature is similar to the previously reported change of bandgap with temperature (2.72 eV at 300 K and 2.83 eV at 80 K) . In contrast, the intensity of emission at 650 nm increases significantly at low temperature.…”

“…CL characterization has the advantage of high excitation energy and high spatial resolution, which is capable of acquiring the excitonic states and defects . As illustrated in Figure a and Figure S4 in the Supporting Information, the CL spectra of different thickness Ga 2 In 4 S 9 flakes reveals a near‐band‐edge emission around 450 nm (2.76 eV) and an additional emission peak around 650 nm (1.91 eV) related to defects or traps below the bandgap . The intensity of near‐band‐edge emission decreases with the decrease of thickness, while the emission peak at 650 nm has no positive correlation, which may be related to the concentration of defects.…”

“…Ternary Ga 2 In 4 S 9 is a layered material with weak van der Waals interaction and reveals n‐type semiconducting behavior . The multinary compound that reveals an unprecendented robust electronic character as well as a wide bandgap close to 2.7 eV with pronounced photosensitivity and temperature‐dependent optical absorption edge opens a new paradigm for UV detection . This is particularly desirable for military and civilian fields .…”

“…Specifically, as a kind of homobimetallic sulfide, the ternary Ga 2 In 4 S 9 is believed to possess novel electronic and optoelectronic properties compared the 2D counterparts . Up to now, only work on bulk Ga 2 In 4 S 9 with a thickness of a few micrometers has been reported, in which bulk Ga 2 In 4 S 9 is obtained by chemical vapor transport . The bulk structure actually hinders their practical application in the field of micro–nano electronic and optoelectronic devices .…”

2D semiconductors towards high-performance ultraviolet photodetection

“…Ternary Ga 2 In 4 S 9 is a layered material with weak van der Waals interaction [187]. More importantly, the multinary compound reveals an unprecedented robust electronic character, as well as a wide bandgap close to 2.7 eV with pronounced photosensitivity and temperature-dependent optical absorption edge, opening a new paradigm for ultraviolet detection [188,189]. Unfortunately, so far, there are few reports on the synthesis of 2D ternary Ga 2 In 4 S 9 flakes with controllable stoichiometry, which may be attributed to the difficulty in selecting optimal homobimetallic precursors.…”