Piezotronic AlGaN nanowire Schottky junctions grown on a metal substrate

The non-centrosymmetric crystal structures of polar-semiconductors comprising GaN, InN, AlN, and ZnO intrigued the scientific community in investigating their potential for a strain-induced nano-energy generation. The coupled semiconducting and piezoelectric properties produce a piezo-potential that modulates the charge transport across their heterostructure interfaces. By using conductive-atomic force microscopy, we investigate the mechanism that gives rise to the piezotronic effect in AlGaN nanowires (NWs) grown on a molybdenum (Mo) substrate. By applying external bias and force on the NWs/Mo structure using a Pt–Ir probe, the charge transport across the two adjoining Schottky junctions is modulated due to the change in the apparent Schottky barrier heights (SBHs) that result from the strain-induced piezo-potential. We measured an increase in the SBH of 98.12 meV with respect to the background force, which corresponds to an SBH variation of 6.24 meV/nN for the semiconductor/Ti/Mo interface. The SBH modulation, which is responsible for the piezotronic effect, is further studied by measuring the temperature-dependent I–V curves from room temperature to 398 K. The insights gained from the unique structure of AlGaN NWs/Mo shed light on the electronic properties of the metal-semiconductor interfaces, as well as on the potential application of AlGaN NW piezoelectric nanomaterials in optoelectronics, sensors, and energy generation applications.

Al-Maghrabi, L., Huang, C., Priante, D., Tian, M., Min, J.-W., Zhao, C., … Ooi, B. S. (2020). Piezotronic AlGaN nanowire Schottky junctions grown on a metal substrate. AIP Advances, 10(5), 055014. doi:10.1063/5.0008112

We acknowledge the financial support from the King Abdulaziz City for Science and Technology (KACST) under Grant No. KACST TIC R2-FP-008. This work was partially supported by the King Abdullah University of Science and Technology (KAUST) baseline Funding No. BAS/1/1614-01-01, MBE equipment Funding Nos. C/M-20000-12-001-77 and KCR/1/4055-01-01, the National Natural Science Foundation of China under Grant No. 61905236, the University of Science and Technology of China (USTC) under Grant No. KY2100000081, the USTC National Synchrotron Radiation Laboratory Grant No. KY2100000099.

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