First-principles calculations for Li, P dopants and vacancy defect in ultra-thin hydrogenated diamond nanofilms: Structural, electronic and optical properties

The substitutional and interstitial phosphor (P) and lithium (Li) dopants, as well as complexes involving these dopants and vacancies, in bilayered hydrogenated diamond are studied using first-principles method. The results show that the substitutional P and interstitial Li are stable in doped diamond nanofilms. On the other hand, the interstitial P and substitutional Li are energetically unfavorable. The calculations on electronic properties indicate that substitutional P and interstitial Li are n-type dopants, while a p-type feature appears, when the dopant interacts with the nearest carbon vacancy. Furthermore, the static refractive index of the ultra-thin diamond system is lower than its bulk counterpart. Our results demonstrate that the electronic and optical properties of the ultra-thin diamond films is potentially tailored with appropriately doping, and an exciting prospect of using such ultra-thin diamond layer are desirable as next-generation nanoelectronics.