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Two-Dimensional Materials in Photoconductive Detectors
Published in Sam Zhang, Materials for Devices, 2023
Yu Duan, Shuanglong Feng, Sam Zhang
The specific detectivity is another critical parameter of the detector, which is used to measure the performance of the detector by normalization. It integrates the detector's responsivity, the effective area of the device, noise, circuit bandwidth, and other important indicators and achieves normalized comparison through formula calculation. Its unit is cm Hz1/2 W−1 or Jones. The higher the value of D* is, the more sensitive the detector is. The formula is:[25]D*=∆f×SNEP
Sensors Using Polymer Films (Construction, Technology, Materials, and Performance)
Published in Gábor Harsányi, Polymer Films in Sensor Applications, 2017
The sensors are described by the specific detectivity, D*, which gives the reciprocal minimum detectable signal power as being equal to the noise power. It is a “figure of merit,” the actual detectivity normalized to unit bandwidth and unit area and is a measure of the signal-to-noise ratio. It can be expressed as D*=(S/N)AΔf/P
Optical Detection and Noise
Published in Chunlei Guo, Subhash Chandra Singh, Handbook of Laser Technology and Applications, 2021
The specific or normalized detectivity (D*) is defined by assuming also that the background signal is proportional to the device area, so that D=D*/AΔf. Specific detectivity is, therefore, usually quoted in units of cm Hz1/2 W−1.
Pyro-phototronic effect enhanced self-powered photodetector
Published in International Journal of Optomechatronics, 2022
Pyro-phototronic effect enhanced photodetectors can be modulated by plasmonic metal nanoparticles (NPs) to obtain tunability of sensitive light waveband. When P-Si/ZnO NWs photodetectors are inserted into a layer of plasmonic Au or Ag NPs between Si and ZnO, spectral insensitivity for the pyroelectric detectors is conquered.[36] The as-fabricated devices decorated with Ag or Au NPs at interface show the best current-response capability at 405 nm or 940 nm respectively. And the wavelength selection ratio is increased by a factor of 80. Response speed of the reported photodetectors can be highly improved through interface modification of plasmonic metal NP. In particular, Si/Ag/ZnO devices display ultrafast rise time of 20 µs under 405 nm light illumination at 825 Hz chopper frequency, whose rise time is 6 times higher than that of the Si/ZnO photodetector. Ultrafast optic-thermal coupling effect induced by LSPR and pyroelectric effect can account for this remarkable enhancement. Plasmonic Au NPs can also be used to enhance UV detection because they can absorb UV light and generate photo-generated electron-hole pairs interband transitions. So, there is a UV photodetector enhanced by pyro-phototronic effect and plasmonic Au NPs. The device architecture has a layered configuration with Au NPs/ZnO/Au film where the sputter-deposited Au NPs and ZnO are photoactive layers. The photoactive layer can display significant absorption of UV light, leading to an increase of photocurrent at 365 nm. Although maximum responsivity and specific detectivity can be obtained as 4.68 A/W and 8.18 × 1011 Jones under a biased condition for the devices, the pyro-phototronic effect from the inherent pyroelectric property of the ZnO contributes to fast photoresponse. The fastest response time is 15 µs without external bias.