Electrical tailoring of the photoluminescence of silicon-vacancy centers in diamond/silicon heterojunctions

Abstract

Charge state regulation of color centers in diamond has attracted considerable attention owing to the difference in their optical emission. To date, to convert the neutrally-charged type to the negatively-charged type in diamond has remained a challenge. To address this issue, (100) micro-crystalline diamond membranes containing silicon vacancy (SiV) centers were deposited on n-type silicon substrates, forming diamond/n-Si heterojunctions. Applying a bias voltage on the heterojunctions was carried out to make carriers transport across the diamond/Si interface. Compared with the non-rectifying diamond/n⁻-Si heterojunction, the diamond/n⁺-Si heterojunction shows a rectification ratio of about two orders of magnitude. The SiV⁻ photoluminescence (PL) intensity remains unchanged at the reverse bias in the diamond/n⁺-Si heterojunction, while it increases by two fold at the forward bias, larger than that in the diamond/n⁻-Si heterojunction. Such PL variation is consistent with the injection current in both heterojunctions. Detailed band diagram analysis reveals that electron tunneling from the substrate to the diamond contributes to a larger forward current and brighter SiV⁻ PL emission in the n⁺-Si heterojunction. Therefore, our work demonstrates that the heterojunction of diamond with heavily doped n-type materials would enable the population increase of negatively-charged color centers via the electron tunneling effect.