Spectral Responsivity and Photoconductive Gain in Thin Film Black Phosphorus Photodetectors

Abstract

We have fabricated black phosphorus photodetectors and characterized their full spectral responsivity. These devices, which are effectively in the bulk thin film limit, show broadband responsivity ranging from <400 nm to the ~3.8 µm bandgap. In the visible, an intrinsic responsivity >7 A/W can be obtained due to internal gain mechanisms. By examining the full spectral response, we identify a sharp contrast between the visible and infrared behavior.In particular, the visible responsivity shows a large photoconductive gain and gate-voltge dependence, while the infrared responsivity is nearly independent of gate voltage and incident light intensity under most conditions. This is attributed to a contribution from the surface oxide.In addition, we find that the polarization anisotropy in responsivity along armchair and zigzag directions can be as large as 10 3 and extends from the band edge to 500 nm. The devices were fabricated in an inert atmosphere and encapsulated by Al 2 O 3 providing stable operation for more than 6 months.

Self‐Healing Cs3Bi2Br3I6 Perovskite Wafers for X‐Ray Detection

“…This lattice strain could be reduced during preparation by annealing at a temperature close to the decomposition temperature of the metal-halide, resulting in somewhat improved performance parameters, however not as good as the aging provides. Such self-healing, which was observed so far for lead-based metal halide perovskites [8,42,43] and is shown here to occur also in Bi-based halides, will be relevant for the lifetime of detectors, which suffer from X-ray irradiation damage. Here, certainly further investigations are required, which could result in an interesting way toward optimization, not only of X-ray detectors as demonstrated here, but also to numerous other devices relying on stable currents and environmental stability by aging technologies.…”

“…They provide an internal amplification mechanism, which is equivalent to photoconductive gain, [18,39,40] as is frequently reported for photodetectors operating in the visible spectral region. [41][42][43] The gain results from an imbalance between carrier drift time and carrier lifetime, which is favored in semiconductors with high trap state densities. A clear evidence for the presence of such an internal gain mechanism is given, when the measured sensitivity correlates to an electron-hole pair creation energy which is smaller than the band gap energy of the semiconductors, such as is the case for the high sensitivity X-ray detector reported in ref.…”

Recent Advances in 2D Materials for Photodetectors

“…In 2019, Wang et al. [ 39 ] fabricated a BP‐based photodetector, with broadband wavelength response from 400 nm to 3.8 µm. But in measurement process, they found BP was not stable and easily affected by water molecules and oxygen molecules of air environment.…”

Mid‐Infrared Photodetector Based on Selenium‐Doped Black Phosphorus

“…These results show that BP doped with Se is a fairly good candidate in the field of midwave IR spectral photodetectors. [ 41 ]…”

“…These results show that BP doped with Se is a fairly good candidate in the field of midwave IR spectral photodetectors. [41] To perform electrical simulation, refractive index (n) and extinction coefficient (k) along xx, yy, and zz tensors have been www.advancedsciencenews.com www.pss-a.com computed and plotted between 0 and 5 eV photon energy in Figure 8.…”