The first-principle study on the formation energies of Be, Mg and Mn doped CuInO<sub>2</sub>

Abstract

Exploring new type of optoelectronic materials has fundamental scientific and practical significance in the development of society and economy. Recently, intense research has focused on the use of the wide band-gap bipolarity semiconductor material CuInO<sub>2</sub> which will allow to the fabrication of that total transparent optoelectronic materials. However, the conductivity of CuInO<sub>2</sub> is significantly lower than other n-type conductivity of other TCOs. As a result, one of the key question is how to improve the electric properties of CuInO<sub>2</sub> by doping method. Motivated by this observation, in this paper, using the first-principles methods, the formation energetics properties of dopant (Be, Mg, Mn) in transparent conducting oxides CuInO<sub>2</sub> were studied within the local-density approximation. Substituting dopant (Be, Mg, Mn) for In, substituting dopant (Be, Mg, Mn) for Cu and dopant as interstitial in their relevant charge state are considered. By systematically calculating formation energies and transition energy level of defect, the calculated results show that, substituting Mg for In does not induce the large structural relaxation. in CuInO<sub>2</sub>. One can expect that substituting the Mg and Mn for In introduces acceptor because the relative lower formation energies, furthermore, Be atoms would be substitute for In atoms when the <i>E</i><sub>f</sub> move to CBM. In addition, the donor-type extrinsic defects(such as substituting dopant for Cu and dopant as interstitial) have difficulty in inducing n-conductivity in CuInO<sub>2</sub> because of their deep transition energy level or the higher formation energies. Considering the transition energy level position, Be<sub>In</sub>, Mg<sub>In</sub>, and Mn<sub>In</sub> have transition energy levels at 0.06, 0.05, and 0.40 eV above the VBM, respectively. Thus, for all the acceptor-type extrinsic defects, substituting Mg for In is the most prominent doping acceptor with relative shallow transition energy levels in CuInO<sub>2</sub> under O-rich condition. Based on our calculated results and discussion mentioned above, in order to increase p-type conductivity in CuInO<sub>2</sub>, we could substitute Mg atoms for In atoms by the sit-selective doping method through atomic layer epitaxy growth or controlling the oxygen partial pressure in the molecular beam epitaxy or metal-organic chemical vapor deposition crystal growth process. The calculation results will not only provide the guide for design of new type In-based optoelectronic materials, but will also further understand the potential properties in CuInO<sub>2</sub>.