Passivation of Layered Gallium Telluride by Double Encapsulation with Graphene

Abstract

Layered semiconductor gallium telluride (GaTe) undergoes a rapid structural transition to a degraded phase in ambient conditions, limiting its utility in devices such as optical switches. In this work, we demonstrate that the degradation process in GaTe flakes can be slowed down dramatically via encapsulation with graphene. Through examining Raman signatures of degradation, we show that the choice of substrate significantly impacts the degradation rate and that the process is accelerated by the transfer of GaTe to hydrophilic substrates such as SiO2/Si. We find that double encapsulation with both top and bottom graphene layers can extend the lifetime of the material for several weeks. The photoresponse of flakes encapsulated in this way is only reduced by 17.6 ± 0.4% after 2 weeks, whereas unencapsulated flakes display no response after this time. Our results demonstrate the potential for alternative, van der Waals material-based passivation strategies in unstable layered materials and highlight the need for careful selection of substrates for 2D electronic devices.

Emerging Two‐Dimensional Tellurene and Tellurides for Broadband Photodetectors

“…As a highly stable tellurium metal in a dry environment at room temperature, GaTe is extensively used in the optoelectronic and semiconductor industries and so on. [106][107][108][109][110][111] The structure of GaTe is diverse, with the material appearing as a monoclinic phase in the bulk state, and it has a hexagonal phase when the layers are reduced to a few or even only one. The monoclinic phase of GaTe appears as a semiconductor with a direct bandgap of 1.7 eV, while the hexagonal phase of GaTe appears as an indirect bandgap, with the VBM shifting toward the Γ point as the number of layers rises rapidly approaching the energy bandstructure of bulk GaTe.…”

Reliable and broad-range layer identification of Au-assisted exfoliated large area MoS2 and WS2 using reflection spectroscopic fingerprints

“…The white light reflection spectra (WLRS) in the range of 400-950 nm were measured by a Raman spectrometer (see the Experimental Section for details). The white light focal spot radius was determined to be 1.72 ± 0.03 µm by the knife edge method [9,50,55] (Figure S2). Figure 1d shows a WLRS mapping on a MoS2 nanofilm with 1-5L regions; the clear boundaries between different regions and the uniform color gamut of the same thickness region indicate the high spatial resolution and good repeatability of this method, respectively.…”

“…Two dimensional (2D) transition metal dichalcogenides (TMDCs), such as MoS2, 2 WS2, MoSe2, and WSe2, have attracted much attention due to their unique optical, electrical, thermal, mechanical and spin properties [1][2][3][4][5][6][7][8][9][10][11] , which are highly dependent on the layer number of the van der Waals structures. Mechanical exfoliation has been the most commonly used method to obtain high-quality single-crystalline monolayer and few-layer 2D materials, although the exfoliated sample size is quite limited.…”

Improving the Efficiency of Gallium Telluride for Photocatalysis, Electrocatalysis, and Chemical Sensing through Defects Engineering and Interfacing with its Native Oxide

“…However, the growth of large‐size, highly crystalline bulk GaTe crystals is particularly complex, due to the presence of solid‐state phase transitions and the more complicated crystal structure than parental Ga chalcogenides. [ 19 ] Furthermore, the poor environmental stability of GaTe, [ 17a , 20 ] with oxidation starting in a timescale of two hours up to a completely oxidized GaTe layer after one week in air, [ 21 ] represents a hurdle for the industrial exploitation of GaTe‐based devices. Accordingly, encapsulation strategies have been recently devised in order to protect active channels in nanodevices, [ 20b,c,21,22 ] although their complexity (encapsulation with graphene, [ 21 ] hexagonal boron nitride (h‐BN) [ 23 ] or Al 2 O 3 , [ 22 ] passivation with ultrathin hydrogen–silsesquioxane film, [ 24 ] surface functionalization with diazonium molecules [ 25 ] ) could be unsuitable for industrial applications.…”