Responsivity

About: Responsivity is a research topic. Over the lifetime, 9918 publications have been published within this topic receiving 186118 citations.

$D$ -Band Total Power Radiometer Performance Optimization in an SiGe HBT Technology

Abstract: A D-band SiGe HBT total power radiometer is reported with a peak responsivity of 28 MV/W, a noise equivalent power (NEP) of 14-18 fW/Hz1/2, and a temperature resolution better than 0.35 K for an integration time of 3.125 ms. The 1/f noise corner of the radiometer is lower than 200 Hz. Fabricated in a developmental technology with 270-GHz fT and 330-GHz/max, it includes a five-stage low-noise amplifier (LNA) with 4-7-GHz bandwidth and over 35 dB of gain centered at 165 GHz, along with a square-law detector with an NEP below 6 pW/Hz1/2 up to 170 GHz. An average system noise temperature of 1645 K is obtained using the Y-factor method and a noise bandwidth of 10 GHz calculated from the measured S21(f) characteristics of the radiometer. The reduced 1/f noise corner frequency in the presence of the amplifier, compared to that of the detector, appears to indicate that, unlike in III-V radiometers, LNA gain fluctuations are not a problem in SiGe HBT radiometers. The circuit consumes 95 mW and occupies 765 × 490 μm2. Wafer mapping of the radiometer sensitivity and of the amplifier gain was performed across different process splits. The mapping results demonstrate that the radiometer can be employed as a relatively simple and area-efficient transistor noise-measure monitor, useful in SiGe HBT vertical profile optimization.

ZnO-based interdigitated MSM and MISIM ultraviolet photodetectors

Abstract: The paper reports the fabrication and characterization of ZnO-based interdigitated metal–semiconductor–metal (MSM) and metal–insulator–semiconductor–insulator–metal (MISIM) ultraviolet photodetectors. The ZnO thin film was grown on a p-type Si 1 0 0 substrate by the sol–gel technique. With applied voltage in the range from −3 to 3 V we estimated the contrast ratio, responsivity, detectivity and quantum efficiency of the photodetectors for an incident optical power of 0.1 mW at 365 nm ultraviolet wavelength. The I–V characteristics were studied and the parameters such as ideality factor, leakage current and barrier height were extracted from the measured data. For Au/Cr/SiO2/ZnO/SiO2/Al (MISIM) structure the product (mχ) of the tunnelling effective electron mass (m) and the mean tunnelling barrier height (χ) was also extracted.

A high performance, visible to mid-infrared photodetector based on graphene nanoribbons passivated with HfO2.

Abstract: Graphene has drawn tremendous attention as a promising candidate for electronic and optoelectronic applications owing to its extraordinary properties, such as broadband absorption and ultrahigh mobility. Nevertheless, the absence of a bandgap makes graphene unfavorable for digital electronic or photonic applications. Although patterning graphene into nanostructures with the quantum confinement effect is able to open a bandgap, devices based on these graphene nanostructures generally suffer from low carrier mobility and scattering losses. In this paper, we demonstrated that encapsulation of an atomic layer deposited high-quality HfO2 film will greatly enhance the carrier mobility and decrease the scattering losses of graphene nanoribbons, because this high-k dielectric layer weakens carrier coulombic interactions. In addition, a photodetector based on HfO2 layer capped graphene nanoribbons can cover broadband wavelengths from visible to mid-infrared at room temperature, exhibiting ∼10 times higher responsivity than the one without a HfO2 layer in the visible regime and ∼8 times higher responsivity in the mid-infrared regime. The method employed here could be potentially used as a general approach to improve the performance of graphene nanostructures for electronic and optoelectronic applications.

Few-layer graphene/ZnO nanowires based high performance UV photodetector.

Abstract: A graphene and zinc oxide nanowires (G/ZnO NWs) based ultraviolet (UV) photodetector presents excellent responsivity and photocurrent gain with detectivity. Graphene due to higher charge carrier transport mobility induces faster response to UV illumination at the interface between ZnO and graphene with improved response and decay times as compared to a ZnO NWs device alone. A linear increase is revealed for both the responsivity and photocurrent gain of the G/ZnO NWs device with the applied bias. These results suggest that the G/ZnO NWs device exhibits great promise for highly efficient UV photodetectors.

(AlGa)_2O_3 solar-blind photodetectors on sapphire with wider bandgap and improved responsivity

Abstract: Single crystallinity (AlGa)2O3 solar-blind photodetectors are epitaxially grown on sapphire. Oxygen pressure during the growth has a great impact on the Al composition in (AlGa)2O3, which is investigated utilizing X-ray photoelectron spectroscopy and X-ray diffraction measurements. Measured transmittance spectra and responsivity demonstrate that (AlGa)2O3 photodetectors achieve a wider bandgap compared to a Ga2O3 device. An (Al0.12Ga0.88)2O3 device obtains 10 times higher photocurrent Iphoto than a Ga2O3 photodetector. However, as Al composition increases, significant Iphoto degradation is observed in an (Al0.35Ga0.65)2O3 photodetector. Meanwhile, an (Al0.35Ga0.65)2O3 device exhibits the stronger persistent photoconductivity compared to the Ga2O3 control device. Analysis shows that defect states in a bandgap of (AlGa)2O3 might be associated with the performance change in (AlGa)2O3 photodetectors.