Large area photodetectors based on InP NWs with InAs/InAsP QWsShow others and affiliations
2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]
Focal plane arrays have a widespread use in infrared imaging, which often rely on cryogenic cooling to curtail the dark current level necessary for a reasonable signal-to-noise ratio. Quantum well (QW) infrared photodetectors are uniform over large areas, but suffer from a severe drawback related to the selection rules for intersubband absorption. An interesting alternative is self-assembled III-V nanowires offering a key advantage owing to the enhanced absorption by optical resonance effects and strain relaxation.We present electrical and optical results from large ensembles of n+-i-n+ InP NWs, axially grown on InP substrates with InAs/InAsP QWs embedded within the i-segment, designed for both interband and intersubband detection. The NWs are contacted in a vertical geometry using 50 nm SiO2 as the insulating layer and ITO as the top contact. We first investigate the crystal quality of the InAsP QWs grown in 180 nm diameter NWs, using PL, CL and TEM. To achieve more abrupt InAs/InAsP QWs, we grow 130 nm diameter NWs and deplete the In present in the Au catalysts. The effect of n-doping on the device performance is studied by fabricating two different NW geometries, with and without an n+-segment grown before the nominal i-segment in the NW. In addition, the position of the QWs within the i-segment is varied to further scrutinize effects related to doping and crystal structure. Finally, we report spectrally resolved photocurrent results from the QWs in the near-infrared region and discuss about the further developments needed for intersubband detection.
Place, publisher, year, edition, pages
2014.
National Category
Condensed Matter Physics Nano Technology
Identifiers
URN: urn:nbn:se:hh:diva-27698OAI: oai:DiVA.org:hh-27698DiVA, id: diva2:785812
Conference
SPIE Optics + Photonics (2014), San Diego, California, USA, 17-21 August, 2014
2015-02-042015-02-042022-06-07Bibliographically approved