Investigation of optical, electrical and optoelectronic properties of SnSe crystals

Abstract

The optical, electrical and optoelectronic properties of tin selenide crystals are of immense significance for application in photodetectors and energy conversion and storage devices. The transition metal chalcogenides possess a layered structure that interacts with each other through van der Waal forces and can also offer sites for intercalation. The low molecular weight materials like GeSe and SnSe are found in an orthorhombic structure. In this article, the optical, electrical and optoelectronic properties of as-grown tin selenide crystals are investigated. The chemical composition of the crystals grown with the aid of direct vapour transport (DVT) technique is confirmed through energy Dispersive analysis of X-rays (EDAX), at the same time the morphological analysis is accomplished using optical microscopy and Scanning Electron Microscopy (SEM). The grown crystals are characterized by powder X-ray diffraction (XRD) method to assess the structural properties of the material. The XRD evaluation found out the orthorhombic structure of the crystals with the space group 16 2h D (P cmn) having lattice parameters a = 11.490 Å, b = 4.440 Å and c = 4.135 Å. The crystallinity of grown samples was verified by transmission electron microscopy (TEM). The single crystalline nature of grown crystals was revealed by SAED pattern. The indirect optical band gap of 1.0065 eV, Urbach energy and steepness parameter are calculated utilising UV-VIS-NIR spectrophotometer. The optical absorption of as-grown SnSe crystals has been measured close to the fundamental absorption edge at room temperature. Both types of transitions, i.e. direct and indirect, are involved in the absorption process. Electrical transport properties like resistivity measurements (parallel and perpendicular path to the c-axis) had been carried out on these crystals within the temperature range 297-673 K. Anisotropy in resistivity measurements in both the directions, i.e. parallel and perpendicular direction to the c-axis was discovered. The p-type semiconducting nature was confirmed with the aid of Hall-effect measurements. For the photodetection properties of SnSe crystals, light source (670 nm) having an intensity of 3 mW/cm 2 at distinctive biasing voltages is used. The outstanding detection properties are revealed from the responsivity, specific detectivity and external quantum efficiency (EQE) of pure SnSe crystals.

Self‐Driven High Performance Broadband Photodetector Based on SnSe/InSe van der Waals Heterojunction

“…In contrast, the devices with ultrafast response speed ≈µs, has graphene as transparency electrode, to greatly facilitate the carrier collection and reduce carrier recombination. [ 7a,15–17,43 ] Moreover, the single cycle I–t curve of the device at 0 V is illustrated in the Figure S9 (Supporting Information), indicating τ r = 1.256 s and τ f = 336 ms, respectively. The device exhibits a comparatively longer response and recovery time under zero bias, attributed to the relatively small built‐in electrical field.…”

Effect of film thickness and evaporation rate on co-evaporated SnSe thin films for photovoltaic applications

“…Due to the excellent electronic and optical properties of binary compounds in transition metals, many scholars have conducted in-depth research in photovoltaic and solar-cell systems. [1][2][3][4][5] Among binary compounds in transition metals, SnSe has great application prospects because SnSe has an orthorhombic crystal structure, 6 which is suitable for solar cells. SnSe is a p-type semiconductor and its high absorption coefficient (10 5 cm À1 ) ensures that solar radiation is absorbed almost completely.…”

Photosensitive Schottky barrier diodes based on Cu/p-SnSe thin films fabricated by thermal evaporation

“…Shiny grey crystals and powder were collected after the growth process. 11,14,22 The thin-film-based metal and semiconductor materials were deposited on a glass substrate using the thermal evaporation technique using a Hind-High Vacuum coating unit (Model No. 12A4D).…”

“…its real stoichiometry varies with temperature. 11 A previous report suggests that SnSe exhibits a p-type nature determined from the Hall effect measurement. 12 Considerable studies have been reported on the deposition of tin selenide thin films, performed using several deposition techniques such as chemical vapour deposition, 13 thermal evaporation techniques, 14 chemical bath deposition, 15 electrodeposition 16 and electrophoresis.…”