Study of photocurrent generation in InP nanowire-based p(+)-i-n(+) photodetectors
Author
Summary, in English
We report on electrical and optical properties of p(+)-i-n(+)photodetectors/solar cells based on square millimeter arrays of InP nanowires (NWs) grown on InP substrates. The study includes a sample series where the p(+)-segment length was varied between 0 and 250 nm, as well as solar cells with 9.3% efficiency with similar design. The electrical data for all devices display clear rectifying behavior with an ideality factor between 1.8 and 2.5 at 300 K. From spectrally resolved photocurrent measurements, we conclude that the photocurrent generation process depends strongly on the p(+)-segment length. Without a p(+)-segment, photogenerated carriers funneled from the substrate into the NWs contribute strongly to the photocurrent. Adding a p(+)-segment decouples the substrate and shifts the depletion region, and collection of photogenerated carriers, to the NWs, in agreement with theoretical modeling. In optimized solar cells, clear spectral signatures of interband transitions in the zinc blende and wurtzite InP layers of the mixed-phase i-segments are observed. Complementary electroluminescence, transmission electron microscopy (TEM), as well as measurements of the dependence of the photocurrent on angle of incidence and polarization, support our interpretations.
Publishing year
2014
Language
English
Pages
544-552
Publication/Series
Nano Reseach
Volume
7
Issue
4
Document type
Journal article
Publisher
Springer
Topic
- Nano Technology
- Condensed Matter Physics
Keywords
- nanophotonics
- nanowires
- infrared (IR)
- photodetectors
- solar cells
Status
Published
ISBN/ISSN/Other
- ISSN: 1998-0124