Characterisation of InGaN by Photoconductive Atomic Force Microscopy.
Thomas F K WeatherleyFabien C-P MassabuauMenno J KappersRachel A OliverPublished in: Materials (Basel, Switzerland) (2018)
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.
Keyphrases
- atomic force microscopy
- high speed
- single molecule
- room temperature
- electron microscopy
- high resolution
- living cells
- fluorescent probe
- ionic liquid
- sensitive detection
- photodynamic therapy
- carbon nanotubes
- magnetic resonance imaging
- electronic health record
- reduced graphene oxide
- big data
- light emitting
- solid phase extraction
- gas chromatography mass spectrometry
- mass spectrometry
- artificial intelligence