Siam Physics Congress 2015

Ga acceptors in SnO2 revisited: A hybrid functional study

21 May 2015, 08:00

3h

Board: CON-06

Poster presentation Condensed Matter Physics Poster-2

Speaker

Mr Nirawith Palakawong (School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; Thailand Center of Excellence in Physics, Commission on Higher Education, Bangkok 10400, Thailand)

Description

SnO${}_2$ is an oxide semiconductor with wide band gap, good transparency, and high thermal and chemical resistances. As-grown SnO${}_2$ usually exhibits $\mathit{\text{n}}$-type conductivity with high carrier concentrations, which is an obstacle to make it $\mathit{\text{p}}$-type. Consequently, applications of SnO${}_2$ for optoelectronics are limited. Group-III elements, such as Al, Ga, and In, are candidates to give $\mathit{\text{p}}$-type conductivity when substituting for Sn in SnO${}_2$. Earlier calculations suggested that the calculated results of these dopants can be shallow or deep depending on the computational details, i.e., the result based on HSE calculations [Phys. Rev. B $\mathbf{\text{79}}$, 245206 (2009)] showed that they are shallow acceptors, on the other hand, PBE0 calculations [J. Mater. Chem. $\mathbf{\text{22}}$, 25236 (2012)] showed that they are all deep. In this work, the possibility of making $\mathit{\text{p}}$-type SnO${}_2$ by Ga was revisited using the HSE functional. Our results show that the acceptor level of Ga${}_{\mathrm{Sn}}$ is actually deep. Therefore, Ga can only serve as compensating acceptor but not a $\mathit{\text{p}}$-type dopant for SnO${}_2$. This conclusion does not change even after the alloying of SnO${}_2$ with Si (Si${}_x$Sn${}_{1-x}$O${}_2$ where $x\sim$ 0.17) to introduce a compressive strain.