Structural, Electronic and Optical Properties of Stanene Doped Beryllium: A First Principle Study

Abstract

Stanene is a 2D hexagonal layer of tin with exceptional electronic and optical properties. However, the semiconductor applications of stanene are limited due to its zero band-gap. However, doping stanene could lead to a band gap opening, which could be a promising material for electronic and optical applications. In this work, optimized structure, electronic band structure, real and imaginary parts of the frequency-dependent dielectric function, electron loss function, and refractive index of stanene substitutionally doped with alkaline earth metal (beryllium) were analyzed using density functional theory (DFT) calculations as implemented in the quantum espresso and yambo suites. A pure stanene has a zero band gap energy, but with the inclusion of spin-orbit coupling in the electronic calculation of pure stanene, the band-gap is observed to open up by 0.1eV. Doping stanene with beryllium opens the band-gap and shifts the Dirac cone from the Fermi level, the band gap opens by 0.25eV, 0.55eV, and 0.8eV when the concentration of Beryllium is 12.5%, 25%, and 37.5% respectively. The Dirac cone vanished when the concentration of the dopant was increased to 50%.  The Fermi level is shifted towards the valence band edge indicating a p-type material. The material absorption shows that SnBe absorption ranges in the visible to the ultraviolet region, The refractive index in stanene doped beryllium (SnBe) was found to be higher than that of pristine stanene, the highest refractive index was 9.2 at SnBe25%. In a nutshell, the results indicate that stanene can be a good material for electronic and optical applications if doped with beryllium.