16,551 research outputs found
Laser scanned image sensors using photoconductors with deep traps
Photoconductor records image when holes and electrons are trapped inside it due to incident photons. Image can be read out by exposing photoconductor to scanning laser beam. Photons from scanning laser empty traps, generating photocurrent. Image information is obtained by detecting this photocurrent synchronously with laser scan
Photoelectric scanner makes detailed work function maps of metal surface
Photoelectric scanning device maps the work function of a metal surface by scanning it with a light spot and measuring the resulting photocurrent. The device is capable of use over a range of surface temperatures
A versatile scanning photocurrent mapping system to characterize optoelectronic devices based on 2D materials
The investigation of optoelectronic devices based on two-dimensional
materials and their heterostructures is a very active area of investigation
with both fundamental and applied aspects involved. We present a description of
a home-built scanning photocurrent microscope that we have designed and
developed to perform electronic transport and optical measurements of
two-dimensional materials based devices. The complete system is rather
inexpensive (<10000 EUR) and it can be easily replicated in any laboratory. To
illustrate the setup we measure current-voltage characteristics, in dark and
under global illumination, of an ultra-thin PN junction formed by the stacking
of an n-doped few-layer MoS2 flake onto a p-type MoS2 flake. We then acquire
scanning photocurrent maps and by mapping the short circuit current generated
in the device under local illumination we find that at zero bias the
photocurrent is generated mostly in the region of overlap between the n-type
and p-type flakes.Comment: 9 pages, 3 figures, 1 table, supporting informatio
Near-field photocurrent nanoscopy on bare and encapsulated graphene
Opto-electronic devices utilizing graphene have already demonstrated unique
capabilities, which are much more difficult to realize with conventional
technologies. However, the requirements in terms of material quality and
uniformity are very demanding. A major roadblock towards high-performance
devices are the nanoscale variations of graphene properties, which strongly
impact the macroscopic device behaviour. Here, we present and apply
opto-electronic nanoscopy to measure locally both the optical and electronic
properties of graphene devices. This is achieved by combining scanning
near-field infrared nanoscopy with electrical device read-out, allowing
infrared photocurrent mapping at length scales of tens of nanometers. We apply
this technique to study the impact of edges and grain boundaries on spatial
carrier density profiles and local thermoelectric properties. Moreover, we show
that the technique can also be applied to encapsulated graphene/hexagonal boron
nitride (h-BN) devices, where we observe strong charge build-up near the edges,
and also address a device solution to this problem. The technique enables
nanoscale characterization for a broad range of common graphene devices without
the need of special device architectures or invasive graphene treatment
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