Direct x-ray detection using thin-film pentacene Schottky diodes

Abstract

Direct x-ray detectors using thermally evaporated pentacene thin-films are fabricated in Schottky and coplanar configurations and are analysed for low x-ray dose rates. In both configurations, the x-ray induced photocurrent is found to be five orders of magnitude greater than the theoretically evaluated threshold value that may reflect possible internal gain mechanism. Coplanar detectors showed unstable x-ray photocurrent characteristics; on the other hand, Schottky photodiode structure showed stable response and thus allowed to proceed for x-ray sensitivity measurements. Pentacene-based Schottky detector presented a decent volume sensitivity of 162.3 μC/mGy/cm3. The high x-ray sensitivity of pentacene Schottky detector can be due to the complete depletion of the thin-film at the operating reverse bias, revealed by transfer characteristics of fabricated pentacene MESFET. Such a reasonably good x-ray photoconversion in low-Z organic semiconducting materials uncovers the possibility of implementing them in x-ray medical dosimetry applications and in wearable electronic technology.

Layered metal-organic chalcogenide thin films for flexible and large-area X-ray direct detection

“…In Figure 4 the LoD value estimated by these samples is compared with the state of the art for detectors based on organic semiconductors [15,[43][44][45][46][47][48] and perovskites active layers in the form of single crystal [3,4,37,38,[49][50][51][52][53][54][55][56][57][58][59][60][61][62] or polycrystalline films [9,10,[63][64][65][66][67][68][69][70][71][72]. Moreover, in the graph it is highlighted the performances achieved by lead-free materials.…”

“…FIGURE 4Limit of Detection-State of the Art. Limit of Detection (LoD) reported in literature for metal halide perovskite single crystals (red)[3,4,37,38,[49][50][51][52][53][54][55][56][57][58][59][60][61][62], organic semiconductor single crystals (green)[43][44][45], perovskite films (blue)[9,10,[63][64][65][66][67][68][69][70][71][72], organic semiconductor films (blue light)[15,[46][47][48] and [AgSePh] ∞ nanocrystalline films (yellow) X-ray detectors. The black shadows indicate the lead-free materials.…”

P‐12.8: TIPS‐pentacene doped PCBM direct high sensitivity X‐ray detector

“…In the work conducted by Gao et al [12], pentacene-based detectors were fabricated employing both vertical and coplanar structures. The resulting X-ray-induced photocurrents exhibited a significant enhancement, surpassing theoretically evaluated thresholds by five orders of magnitude, indicative of an inherent organic X-ray gain mechanism within the semiconductor [13].…”