Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint First principle study of the conductive type stability in Sn, Li and Li-Ni doped ZnO nanosheet Chumpol Supatutkul, Sittichain Pramchu, Atchara Punya Jareonjittichai ⁎ , Yongyut Laosiritaworn Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand ARTICLE INFO Keywords: ZnO nanosheet Sn-doped ZnO Li-doped ZnO Li-Ni doped ZnO Density functional theory ABSTRACT In this study, the Sn, Li and Li-Ni doped ZnO nanosheet were studies using density functional theory implemented in Quantum espresso package. The electrical and optical properties of these doping effects on ZnO nanosheet were studied using Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. The dopant ions were substituted on Zn sites in hexagonal ZnO nanosheets. The results showed that, for the n-type doping, the Sn- doped ZnO nanosheet is the most stable under O-poor condition compared with the Li doping and Li-Ni co- doping and has donor level at 2.29 eV below conduction band minimum (CBM). On the other hand, for the p- type doping, Li-doped ZnO nanosheet has acceptor level at 0.68 eV above valence band maximum (VBM) and is more energetic favorable than the Li-Ni doped ZnO in O-poor condition. Therefore, this density functional investigation shows that the high stability of ZnO nanosheets can be achieved for both p-type and n-type conductivity depending on the designed growth condition. These results then suggest the possibility to produce both conductive types in ZnO nanosheet for implementation as p-n junction in miniaturized electronics devices. 1. Introduction The doping of wide band-gap oxide semiconductor has been attracting great interest in the development of transparent oxide optoelectronic devices [1,2]. One of the prominent candidates is the doped zinc oxide semiconductors as they yield high transparency in visible spectral range and can also be modified as both n-type and p- type conductivities [3]. Furthermore, the realization of p-n type homojunction in ZnO allows the material to be implemented in UV- optoelectronics and transparent electronics [4,5]. However, its stability and reproducibility are still the problems [6]. Usually, the ZnO can be achieved in n-type semiconductor by doping group-IV elements such as Sn, Mn and S. On the other hands, the p-type ZnO can be obtained by doping group-I elements such as Li, Na and K, but it has somewhat high structural instabilities and the high resistance of shallowness acceptor formation [7,8]. Nevertheless, a recent study suggests that the p-type ZnO can be achieved by co-doping ZnO thin films with Li-Ni [9]. In addition, compared with other metal oxides, ZnO are available in diverse nanostructures such as nanowire, nanotube, nanosheet and so on, where their electrical and optical properties can be tuned differently from those of bulk ZnO. Therefore, the doping of ZnO in nanostructure could be a challenging topic in miniaturized electronics devices with applications based on each different p-n junction characteristics. Therefore, in this work, we have investigated p-type and n-type conductivities of the doped ZnO nanosheet using density functional theory (DFT). The objective is to comprehend the main mechanism how Sn, Li and Li-Ni dopants affect the stability and electronic properties of the ZnO nanosheet, which could be suggested as a smart material for nanoelectronics. 2. Materials and methods In this work, electrical properties of the ZnO nanosheet were investigated using density functional theory (DFT) with the pseudopo- tential plane wave method implemented in Quantum Espresso package [10]. The electronic calculation was performed using Heyd-Scuseria- Ernzerhof (HSE) hybrid density functional, which mixes the exact non- local exchange of Hartree-Fork (HF) theory with the local exchange and correlation potential of Perdrew-Burke-Ernzerhof (PBE) functional from generalized gradient approximation (GGA) [11,12]. As the HF method lacks of inter-electronic correlation and its exchange interac- tion is very long ranged, the shorter range GGA exchange interaction was considered to partially replace the non-local HF exchange. The percentage of mixing ratio between GGA and HF exchange can be determined from the calibration of electrical properties and the structural parameters with the data base of interested element. For http://dx.doi.org/10.1016/j.ceramint.2017.05.276 ⁎ Corresponding author. E-mail address: atcharapunya@gmail.com (A.P. Jareonjittichai). Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2017 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Supatutkul, C., Ceramics International (2017), http://dx.doi.org/10.1016/j.ceramint.2017.05.276