Scanning spreading resistance microscopy (SSRM) was performed on non-intentionally doped (nid) ZnO nanowires (NWs) grown by metal-organic chemical vapor deposition in order to measure their residual carrier concentration. For this purpose, an SSRM calibration profile has been developed on homoepitaxial ZnO:Ga multilayer staircase structures grown by molecular beam epitaxy. The Ga density measured by SIMS varies in the 1.7 × 1017 cm−3 to 3 × 1020 cm−3 range. From measurements on such Ga doped multi-layers, a monotonic decrease in SSRM resistance with increasing Ga density was established, indicating SSRM being a well-adapted technique for two dimensional dopant/carrier profiling on ZnO at nanoscale. Finally, relevant SSRM signal contrasts were detected on nid ZnO NWs, and the residual carrier concentration is estimated in the 1–3 × 1018 cm−3 range, in agreement with the result from four-probe measurements.
Access to residual carrier concentration in ZnO nanowires by calibrated scanning spreading resistance microscopy
L. Wang, J. M. Chauveau, R. Brenier, V. Sallet, F. Jomard, C. Sartel, G. Brémond; Access to residual carrier concentration in ZnO nanowires by calibrated scanning spreading resistance microscopy. Appl. Phys. Lett. 28 March 2016; 108 (13): 132103. https://doi.org/10.1063/1.4945100
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