nn7b07028_si_001.pdf (980.68 kB)
Mid-Wave Infrared Photoconductors Based on Black Phosphorus-Arsenic Alloys
journal contribution
posted on 2017-10-31, 00:00 authored by Matin Amani, Emma Regan, James Bullock, Geun Ho Ahn, Ali JaveyBlack
phosphorus (b-P) and more recently black phosphorus-arsenic
alloys (b-PAs) are candidate 2D materials for the detection of mid-wave
and potentially long-wave infrared radiation. However, studies to
date have utilized laser-based measurements to extract device performance
and the responsivity of these detectors. As such, their performance
under thermal radiation and spectral response has not been fully characterized.
Here, we perform a systematic investigation of gated-photoconductors
based on b-PAs alloys as a function of thickness over the composition
range of 0–91% As. Infrared transmission and reflection measurements
are performed to determine the bandgap of the various compositions.
The spectrally resolved photoresponse for various compositions in
this material system is investigated to confirm absorption measurements,
and we find that the cutoff wavelength can be tuned from 3.9 to 4.6
μm over the studied compositional range. In addition, we investigated
the temperature-dependent photoresponse and performed calibrated responsivity
measurements using blackbody flood illumination. Notably, we find
that the specific detectivity (D*) can be optimized
by adjusting the thickness of the b-P/b-PAs layer to maximize absorption
and minimize dark current. We obtain a peak D* of
6 × 1010 cm Hz1/2 W–1 and 2.4 × 1010 cm Hz1/2 W–1 for pure b-P and b-PAs (91% As), respectively, at room temperature,
which is an order of magnitude higher than commercially available
mid-wave infrared detectors operating at room temperature.