Overcoming doping bottleneck by using surfactant and strain

Abstract

Overcoming the doping bottleneck in semiconductors, especially in wide band gap semiconductors, has been a challenge in semiconductor physics for many years. In this paper, we review some recent progresses in enhancing doping by surfactant and strain. We show that surfactant and strain are two effective approaches to enhance dopant solubility in epitaxial growth. The surfactant can introduce an energy level deep inside the band gap, making the host compound less stable, thus lower the formation energy of the intentional dopant. The strain enhanced doping is based on the observation that dopant induces volume change in the host. If the external strain is in the same direction as the dopant induced volume change, the formation energy of the dopant is reduced. This effect can be used to tune doping sites, thus doping type, in a host. A hybrid method to both include strain and surfactant is proposed, which can be a promising general method to further enhance doping.