Thin Films of SiP Lamellar Alloys: A First Step toward 2D SiP

Abstract

We investigate the structural and vibrational properties of Si:P thin films obtained by coevaporation of Si and P in ultra-high vacuum at room temperature followed by rapid thermal annealing. The thermal crystallization of the films was followed by Raman spectroscopy.Annealing at temperatures larger than 950 °C leads to the formation of crystalline phases.Density functional theory calculations of the vibrational modes allow us to identify orthorhombic SiP. Electron energy loss spectroscopy combined with energy dispersive spectroscopy give evidence of a plasmon signature of the SiP phase. The distribution of the crystalline phases in the film was imaged by energy filtered transmission electron microscopy.Both Si and SiP areas having sizes of a few microns are found to coexist in the films. Highresolution scanning transmission imaging provides a clear evidence of the lamellar structure while spatially resolved electron energy loss spectroscopy allows us to obtain a chemical mapping for both Si and P atoms, which agrees quite well with the orthorhombic structure of SiP. Our results represent an important first step on the way to obtain 2D SiP, a promising new material for which a direct bandgap has been predicted.

Influence of phosphorus on the growth and the photoluminescence properties of Si-NCs formed in P-doped SiO/SiO2 multilayers

“…It is worth noting that alloying at the nanoscale has not been observed in this study, while for higher P contents, the formation of SiP 2 nanocrystals inside a SiO 2 matrix has been reported. 29 For P concentrations larger than 0.1 at.%, the Si-NCs size increase and size distribution can be interpreted by a softening of the SiO 2 matrix induced by P impurities, as already suggested. 30 Our results are in good agreement with the P-induced Si-NCs size increase from 4 to 8 nm obtained from the phase separation in P-doped silicon-rich silicon oxide produced by cosputtering with a P concentration of 0.5 at.%.…”

SiP Nanosheets: A Metal-Free Two-Dimensional Photocatalyst for Visible-Light Photocatalytic H2 Production and Nitrogen Fixation

“…The strong peaks at 13.1°, 26.02°, 31.09°, 52.1°and 56.2°correspond to the (002), (004), (044), (200) planes and (1111) direction, respectively. 25 The SiP NSs does not exhibit any new peak, but all peaks weaken as compared with bulk SiP, confirming the decreased thickness of SiP NSs. Generally, 2D materials exhibit a layer number dependent Raman peaks, and thus Raman spectra was performed on both bulk SiP and SiP NSs.…”

“…: 073-1251). The strong peaks at 13.1°, 26.02°, 31.09°, 52.1° and 56.2° correspond to the (002), (004), (044), (200) planes and (1111) direction, respectively . The SiP NSs does not exhibit any new peak, but all peaks weaken as compared with bulk SiP, confirming the decreased thickness of SiP NSs.…”

“…Figure S7 compares the high-resolution Si 2p XPS spectra of bulk SiP and SiP NSs, demonstrating quite similar features with two peaks of Si 0+ and Si 4+ at 99.9 and 103.8 eV, respectively . For bulk SiP, the P 2p spectra illustrated in Figure S8 can be fitted with three peaks located at 130.2, 130.9, and 134.2 eV, which can be attributed to the P 2p 3/2 , P 2p 1/2 , and P–O bond, respectively . The peak of the P–O bond indicates the presence of a slight surface oxidation in bulk SiP.…”

Defective 2D silicon phosphide monolayers for the nitrogen reduction reaction: a DFT study

“…38 Moreover, experimentally-achieved thin films of SiP lamellar alloys were prepared by co-evaporation of Si and P in ultrahigh vacuum at room temperature followed by rapid thermal annealing, which presents an important first step towards 2D SiP. 39 SiP monolayers are also known to possess high dynamical and thermodynamic stability. 37,40 Interestingly, SiP undergoes a transition from an indirect band gap to a direct band gap of approximate 2.60 eV when thinned from bulk to a monolayer.…”