Soft X‐ray Detectors Based on SnS Nanosheets for the Water Window Region

Abstract

The structural characteristics of biological specimens, such as wet proteins and fixed living cells, can be conveniently probed in their host aqueous media using soft X‐rays in the water window region (200–600 eV). Conventional X‐ray detectors in this area exhibit low spatial resolution, have limited sensitivity, and require complex fabrication procedures. Here, many of these limitations are overcome by introducing a direct soft X‐ray detector based on ultrathin tin mono‐sulfide (SnS) nanosheets. The distinguishing characteristic of SnS is its high photon absorption efficiency in the soft X‐ray region. This factor enables the fabricated soft X‐ray detectors to exhibit excellent sensitivity values on the order of 104 μCGyVac−1 cm−2 at peak energies of ≈600 eV. The peak signal is found to be sensitive to the number of stacked SnS layers, with thicker SnS nanosheet assemblies yielding a peak response at higher energies and with peak sensitives of over 2.5 × 104 μCGyVac−1 cm−2 at 1 V. Detailed current–voltage and temporal characteristics of these detectors are also presented. These results showcase the excellent performance of SnS nanosheet‐based soft X‐ray detectors compared to existing direct soft X‐ray detectors, including that of the emerging organic–inorganic perovskite class of materials.

Silver Ions Assisted Inversion Temperature Crystallization of 2D Cs3Bi2Br9 Nanoflakes for Highly Sensitive X‐Ray Detection

“…An obvious drop step occurs in the range of 450–500 nm of incident light due to the bandgap absorption ( Figure a). To further calculate bandgap of 2D Cs 3 Bi 2 Br 9 nanoflakes, we also give the relationship between hν and αhν according to the Kubelka‐Munk equation [ 26 ] $$$$\begin{equation}\alpha h\nu = A{(h\nu - Eg)}^n\end{equation}$$$$where α is the absorption coefficient recorded from Figure 4a, E g is bandgap energy, n = 2 means that measured materials have a direct bandgap. The direct bandgap of 2D Cs 3 Bi 2 Br 9 nanoflakes is 2.57 eV according to the fitting results.…”

Trap States Ruling Photoconductive Gain in Tissue‐Equivalent, Printed Organic X‐Ray Detectors

“…Other recent results with thin-film X-ray detectors based on organic small molecules, polymers, hybrid perovskites, tin mono-sulfide (SnS) nanosheets, both flexible and rigid are listed in Table T4 in the Supporting Information. [26][27][28][29][30][31][32][33] It is important to note that such high sensitivities have been achieved upon irradiation of tens of seconds, which guarantees the full activation of the PG mechanism and the saturation of the effect. This mechanism of detection is based on the active trap states' characteristic lifetimes, leading to very long rise and fall times.…”

Printable Perovskite Diodes for Broad‐Spectrum Multienergy X‐Ray Detection

“…These results validate the excellent sensitivity of these devices toward soft X-rays, with their performance being, to the best of our knowledge, the highest among all reported soft X-ray detectors (see Table S3, Supporting Information). [22,23] The excellent response characteristics are directly attributed to the efficient transport properties of the perovskite, its large soft X-ray attenuation coefficient, and the high flux of the synchrotron X-ray beam.…”

“…The short response time observed here indicates effective carrier transport, low levels of trapping, and good carrier extraction. [ 22 ] Moreover, these values lend themselves to detectors that can provide near real‐time detection at ≈100's Hz scan rates.…”