HgTe nanocrystals, thanks to quantum confinement, present a broadly tunable band gap all over the infrared spectral range. In addition, significant efforts have been dedicated to the design of infrared...
In this paper, a full set of structural, optical and electrical characterizations performed on midwave infrared barrier detectors based on a Ga-free InAs/InAsSb type-II superlattice, grown by molecular beam epitaxy (MBE) on a GaSb substrate, are reported and analyzed. a Minority carrier lifetime value equal to 1 µs at 80 K, carried out on dedicated structure showing photoluminescence peak position at 4.9 µm, is extracted from a time resolved photoluminescence measurement. Dark current density as low as 3.2 × 10−5 A/cm2 at 150 K is reported on the corresponding device exhibiting a 50% cut-off wavelength around 5 µm. A performance analysis through normalized spectral response and dark current density-voltage characteristics was performed to determine both the operating bias and the different dark current regimes.
As the field of nanocrystal-based
optoelectronics matures, more
advanced techniques must be developed in order to reveal the electronic
structure of nanocrystals, particularly with device-relevant conditions.
So far, most of the efforts have been focused on optical spectroscopy,
and electrochemistry where an absolute energy reference is required.
Device optimization requires probing not only the pristine material
but also the material in its actual environment (i.e., surrounded
by a transport layer and an electrode, in the presence of an applied
electric field). Here, we explored the use of photoemission microscopy
as a strategy for operando investigation of NC-based
devices. We demonstrate that the method can be applied to a variety
of materials and device geometries. Finally, we show that it provides
direct access to the metal–semiconductor interface band bending
as well as the distance over which the gate effect propagates in field-effect
transistors.
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