Characterisation of InGaN by photoconductive atomic force microscopy

Thomas F. K. Weatherley, Fabien C.-P. Massabuau, Menno J. Kappers, Rachel A. Oliver

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
16 Downloads (Pure)

Abstract

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.
Original languageEnglish
Article number1794
Number of pages11
JournalMaterials
Volume11
Issue number10
DOIs
Publication statusPublished - 21 Sept 2018

Keywords

  • InGaN
  • photoconductive atomic force microscopy
  • dislocations

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