Be,Mg,Mn掺杂CuInO_2形成能的第一性原理研究

研制开发新型的光电材料对促进社会经济发展具有重要的科学意义和实用价值.利用宽禁带CuInO_2铟基材料实现全透明光电材料是目前深入研究的热点.通过基于密度泛函的第一性原理计算方法,本文计算出掺杂元素Mg, Be, Mn在CuInO_2的形成能.计算结果表明,施主类缺陷(如掺杂元素替代Cu原子或进入间隙位置)由于较高的形成能和较深的跃迁能级,很难在CuInO_2材料中出现N型导电;而受主缺陷中,在氧原子化学势极大的情况下, Mg原子替代In能成为CuInO_2理想的受主缺陷.计算结果可为制备性能优异的CuInO_2材料提供指导.

The first-principle study on the formation energies of Be,Mg and Mn doped CuInO2

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 CuInO₂ which will allow to the fabrication of that total transparent optoelectronic materials. However, the conductivity of CuInO₂ 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 CuInO₂ 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 CuInO₂ 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 CuInO₂. 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 E_f 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 CuInO₂ because of their deep transition energy level or the higher formation energies. Considering the transition energy level position, Be_In, Mg_In, and Mn_In 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 CuInO₂ under O-rich condition. Based on our calculated results and discussion mentioned above, in order to increase p-type conductivity in CuInO₂, 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 CuInO₂.