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# Spatial mapping of band bending in semiconductor devices using in situ quantum sensors

## Abstract

Local variations in the charge distribution at semiconductor interfaces can lead to energy level band bending in the structure’s band diagram. Measuring this band bending is important in semiconductor electronics and quantum technologies, but current methods are typically only surface sensitive and are unable to probe the extent of band bending at a depth within the semiconductor. Here, we show that nitrogen–vacancy centres in diamond can be used as in situ sensors to spatially map band bending in a semiconductor device. These nitrogen–vacancy quantum sensors probe the electric field associated with surface band bending, and we map the electric field at different depths under various surface terminations. Using a two-terminal device based on the conductive two-dimensional hole gas formed at a hydrogen-terminated diamond surface, we also observe an unexpected spatial modulation of the electric field, which is attributed to the interplay between charge injection and photo-ionization effects (from the laser used in the experiments). Our method offers a route to the three-dimensional mapping of band bending in diamond and other semiconductors that host suitable quantum sensors.

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## Data availability

The data underlying the present work are available upon request from the corresponding authors.

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## Acknowledgements

We thank M. Barson, D. Simpson and L. Hall for useful discussions. We acknowledge support from the Australian Research Council (grants CE110001027, DE170100129, FL130100119, DP170102735). J.-P.T acknowledges support from the University of Melbourne through an Early Career Researcher Grant. D.A.B, A.T, S.E.L and C.T.-K.L are supported by an Australian Government Research Training Program Scholarship. This work was performed in part at the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the Australian National Fabrication Facility (ANFF).

## Author information

Authors

### Contributions

NV measurements and analysis were performed by D.A.B and J.-P.T, with inputs from M.W.D. The devices were fabricated by N.D and D.A.B, H-terminated by A.T and A.S, and electrically characterized by C.T-K.L and B.C.J. The band bending model was developed by N.D with inputs from D.A.B, J.-P.T, A.S and L.C.L.H. All authors contributed to interpreting the data and writing the manuscript.

### Corresponding authors

Correspondence to L. C. L. Hollenberg or J.-P. Tetienne.

## Ethics declarations

### Competing interests

The authors declare no competing interests.

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## Supplementary information

### Supplementary Information

Supplementary Tables 1 and 2, Supplementary Figures 1–15, Supplementary Methods 1 and 2, and Supplementary Data 1–3

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Broadway, D.A., Dontschuk, N., Tsai, A. et al. Spatial mapping of band bending in semiconductor devices using in situ quantum sensors. Nat Electron 1, 502–507 (2018). https://doi.org/10.1038/s41928-018-0130-0

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