Characterisation of InGaN by Photoconductive Atomic Force Microscopy.
Weatherley, Thomas FK
Kappers, Menno J
Oliver, Rachel A
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Weatherley, T. F., Massabuau, F. C., Kappers, M. J., & Oliver, R. A. (2018). Characterisation of InGaN by Photoconductive Atomic Force Microscopy.. Materials (Basel), 11 (10) https://doi.org/10.3390/ma11101794
Nanoscale structure has a large effect on the optoelectronic properties of InGaN, a material vital for energy saving technologies such as light emitting diodes. Photoconductive atomic force microscopy (PC-AFM) provides a new way to investigate this effect. In this study, PC-AFM was used to characterise four thick (∼130 nm) In x Ga 1 - x N films with x = 5%, 9%, 12%, and 15%. Lower photocurrent was observed on elevated ridges around defects (such as V-pits) in the films with x ≤ 12 %. Current-voltage curve analysis using the PC-AFM setup showed that this was due to a higher turn-on voltage on these ridges compared to surrounding material. To further understand this phenomenon, V-pit cross sections from the 9% and 15% films were characterised using transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. This identified a subsurface indium-deficient region surrounding the V-pit in the lower indium content film, which was not present in the 15% sample. Although this cannot directly explain the impact of ridges on turn-on voltage, it is likely to be related. Overall, the data presented here demonstrate the potential of PC-AFM in the field of III-nitride semiconductors.
European Research Council (279361)
Engineering and Physical Sciences Research Council (EP/M010589/1)
External DOI: https://doi.org/10.3390/ma11101794
This record's URL: https://www.repository.cam.ac.uk/handle/1810/285148
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/