Enhancing n-type doping in diamond by strain engineering

The utilization of diamond, the ultimate semiconductor, in electronic devices is challenging due to the difficulty of n-type doping. Phosphorus (P)-doped diamond, the most prevalent type of n-type diamond, is still limited by the low solubility of P dopant and undesirable compensating defects such as vacancy defects and hydrogen incorporation. In order to overcome this limitation, strain engineering is introduced to the n-type P-doped diamond theoretically in this work. Uniaxial, equibiaxial, and hydrostatic triaxial strains are applied to the P-doped diamond. The formation energy, charge transition level, defect binding energy and other physical properties of the P-doped diamond are then calculated based on first-principles calculations. The results show that uniaxial, equibiaxial, and hydrostatic triaxial tensile strain can reduce the formation energy and the donor ionization energy of P dopant, and also reduce the binding energy of phosphorus–vacancy (PV) and phosphorus–hydrogen (PH) defects. Our results indicate that under tensile strain, the solubility of the P dopant and the n-type conductivity of the P-doped diamond can be increased, and the formation of compensating defects can be suppressed. Therefore, strain engineering is anticipated to be used to enhance the n-type characteristics of the P-doped diamond, facilitating its application in electronic devices.