Why Te Doping Can Break the Traditional n-Type Doping Limit of Silicon.

We report a theoretical investigation of the impact of hyperdoping with chalcogens (Se and Te) and pnictogens (P and As) on free-carrier concentrations of Si, employing density functional theory calculations. Our results illustrate that isolated substitutional chalcogens in moderately doped Si function as deep donors that are difficult to ionize at room temperature, unlike isolated substitutional pnictogens. The pairing of substitutional defects is found to be energetically favorable for every dopant element, implying that the concentration of substitutional pairs can be significant in hyperdoped Si.