Long-wavelength intersubband quantum disc-in-nanowire photodetectors with normal incidence photoresponse

Research output: Contribution to conferenceAbstract


Semiconductor nanowire (NW) technology has emerged as a key facilitator of novel optoelectronics e.g. solar cells, photodetectors and LEDs. The functional wavelength range of current NW-based photodetectors is typically limited to the visible/
near-infrared region. In this work, we present the first ever reported electrical and optical characteristics of longwavelength IR photodetectors based on large
square millimeter ensembles of vertically grown and processed InAsP/InP heterostructure NWs grown on InP substrates1. More specifically, the MOVPE-grown
NWs comprise single or multiple InAsP quantum discs (QDiscs) axially embedded in an n+-i-n+ geometry. The NWs are contacted together in a vertical geometry
by uniformly depositing a thin insulating SiO2 layer, selective etching of the oxide from the tip of the NWs followed by sputtering of ITO as a common top
contact to all NWs. Using Fourier transform photocurrent spectroscopy, we demonstrate a photoresponse extending from the visible to far infrared1,2.
In particular, the infrared response from 3-20 μm is enabled by intersubband transitions in the lowbandgap InAsP quantum discs synthesized axially
within the InP NWs. The detector elements exhibit an unexpected sensitivity to normal incident radiation, apparently in contradiction to well-known selection rules
for intersubband transitions in quantum wells. From in-depth 2D and 3D optical simulations we attribute this result to an excitation of the longitudinal component of
optical modes in the photonic crystal formed by the nanostructured portion of the detectors. Key advantages with the proposed design include a large degree of
freedom in choice of material compositions, enhanced optical resonance effects due to periodically ordered NW arrays and the compatibility with silicon substrates.
We believe that our novel detector design offers a route towards monolithic integration of compact and sensitive broadband III-V NW detectors with main-stream
silicon technology which could seriously challenge existing commercially available photodetectors.


Original languageEnglish
Publication statusPublished - 2018
Publication categoryResearch
EventQSIP 2018
Quantum Structure Infrared Photodetectors Conference
- Vår Gård in Saltsjöbaden, stockholm, Sweden
Duration: 2018 Jun 162020 May 21


ConferenceQSIP 2018
Quantum Structure Infrared Photodetectors Conference
Internet address