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

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.

Automated summary

The regulation of charge state in color centers of diamond has been a subject of interest due to their different optical emissions. By depositing microcrystalline diamond membranes containing silicon vacancy centers on n-type silicon substrates, researchers have achieved a rectification ratio of two orders of magnitude higher in diamond/n(+)-Si heterojunctions compared to diamond/n(-)-Si heterojunctions. Detailed analysis of the band diagram showed that electron tunneling from the substrate to the diamond contributed to a larger forward current and brighter photoluminescence emission in the n(+)-Si heterojunctions. This work demonstrates the potential of increasing the population of negatively-charged color centers in diamond through the use of heavily-doped n-type materials.