Band Gap Engineering of SnO₂ by Epitaxial Strain: Experimental and Theoretical Investigations

Abstract

The effect of mis-match strain on the structural, electronic, and optical properties in SnO2 epitaxial thin films has been systematically investigated by the experimental and theoretical methods. Our results indicate that the tensile strain exists in the thin film and decreases with the thickness of epitaxial samples. Besides, the optical band gap significantly reduces with increasing the tensile strain in the bc plane. Our hybrid functional calculations present that the narrowing of band gap of SnO2 under tensile strain is due to the weakening of bonding and antibonding split, which results from the disorder of SnO6 octahedra, and the biaxial strain is found to be more efficient than the uniaxial strain for tuning the band gap of SnO2.

Control of SnO2 films by epitaxy and helium implantation

“…On the other hand, films grown with varying thickness on sapphire substrates are under biaxial (2D) strain due to the relaxation of epitaxial mismatch stress. In this case an increase of the optical band gap has been found [14,15]. However, in contrast to these two cases we find here that triaxial (3D) volumetric strain due to He implantation of films grown on MgO (111) substrates doesn't change the band gap significantly.…”

“…This means that the out-of-plane lattice parameter c is increasing due to the incorporation of the He into the lattice. The increase from the as-grown to the 20x10 15 He/cm 2 dosed film is from 4.693 Å to 4.719 Å, which corresponds to an increase of about 0.6%. The in plane lattice parameter a was calculated from 101 reflection (Figure 3b) of SnO 2 , a = 4.710 Å for the undosed film and a = 4.744 Å for the film with 20E 15 dose of helium implantation.…”

Microwave assisted synthesis of hierarchical Pd/SnO2 nanostructures for CO gas sensor

“…Semiconductor oxides are fundamental to the development of functional materials, smart devices, and portable systems. These oxide materials have two unique structural features: mixed cation valences and an adjustable oxygen deficiency, which create and tune many novel physical and chemical properties [6]. The prospect of various semiconductor oxides continues to drive research toward improve the performance of the semiconducting materials utilized in gas detection.…”

Synthesis and Optical Properties of SnO2 Structures with Different Morphologies via Hydrothermal Method

“…Figure 6(b) illustrates the UV-Vis absorption spectra of SnO 2 nanosheets and hollow microspheres. Their band gap can be determined by the Tauc plot, which is a widely used method by many researchers (Ref [31][32][33]. The equation for the Tauc plot is written as (ahm) 2 = A(hm E g ), where a, A, and hm are absorption coefficient, constant, and photon energy, respectively.…”