Efficient generation of single photons on demand at a high repetition rate is a key to the practical realization of quantum-communication networks and optical quantum computations. Color centers in diamond and related wide-band-gap semiconductors are considered to be the most promising candidates for building such single-photon sources due to their outstanding emission properties at room temperature. However, efficient electrical excitation of color centers in most materials remains a challenge due to the inability to create a high density of free carriers. We predict a superinjection effect in diamond p-i-n diodes. By employing a comprehensive theoretical approach, we numerically demonstrate that one can overcome the doping problem in diamond and inject four orders of magnitude more electrons into the i region of the diamond p-i-n diode than the doping of the n region allows. This high density of free electrons can be efficiently used to boost the single-photon electroluminescence process and enhance the brightness of the diamond single-photon source by more than three orders of magnitude. Moreover, we show that such a high single-photon emission rate can be achieved at exceptionally low injection current densities of only $0.001\mathrm{A/m}{\mathrm{m}}^2$, which creates the backbone for the development of low-power and cost-efficient diamond quantum optoelectronic devices for quantum information technologies.

• Received 5 January 2018
• Revised 8 April 2019

DOI:https://doi.org/10.1103/PhysRevApplied.12.024013