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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Impact of post deposition annealing of ZrO <sub/>2</sub> insulating layer on the performance of GaN metal-semiconductor-metal ultraviolet photodetectors
摘要： GaN metal–semiconductor–metal (MSM) ultraviolet photodetectors without and with annealed ZrO2 insulating layers are successfully fabricated. It is found that the dark current is reduced by 3 times post annealing of the oxide layer. GaN MSM photodetectors exhibit large internal gain which can be explained by considering the presence of hole traps in oxide layer. Further, reduction in gain and increase in transient response time of photodetectors post annealing of ZrO2 layer reveal that the density of shallow trap states is considerably reduced by the annealing step. It is noticed that though the response of all the states is affected by the annealing but the fast component of photoresponse is rather severely hampered. The present investigations clearly demonstrate that reduction of dark current is not the sole criteria for improving the performance of a photodetector. Rather, transient response of the device and hence the band width of the device along with the leakage current and gain should be taken into the consideration for qualifying the overall performance of the photodetectors.
关键词： Photoresponse,GaN,Schottky diodes,Responsivity,I-V
更新于2025-09-16 10:30:52
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Drift-induced Nonreciprocal Graphene Plasmonics
摘要： We present a detailed investigation of the responsivity and the noise in room temperature THz direct detectors made of YBa Cu O (YBCO) thin-film nano-bolometers. The YBCO nano-bolometers are integrated with planar spiral antennas covering a frequency range from 100 GHz to 2 THz. The detectors were characterized at 1.6 THz, 0.7 THz, 400 GHz and 100 GHz. The maximum electrical responsivity of 70 V/W and a minimum noise equivalent power (NEP) of 50 pW/Hz were measured, whereas the highest optical responsivity was 45 V/W. The noise in nano-bolometers is independent on the device volume and for a given modulation frequency and a dc voltage.
关键词： THz detectors,YBa Cu O (YBCO) film,responsivity,room temperature operation,Bolometer
更新于2025-09-16 10:30:52
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Improvement in Self-Powered GaN-based Symmetric Metal-Semiconductor-Metal Ultraviolet Photodetectors by Using Phenol-Functionalized Porphyrin Organic Molecules
摘要： Organic molecular monolayers have been used for improving the performance of various electronic device structures. In this work, the concept of organic molecular surface modification is applied for improving the performance and the self-power quality of GaN-based symmetric Metal-Semiconductor-Metal (MSM) Ultraviolet (UV) Photodetectors (PDs). Organic molecules of phenol-functionalized-metallated-Porphyrin (Zn-TPPOH) have been adsorbed on GaN epitaxial layers and Ni/Zn-TPPOH/GaN/Zn-TPPOH/Ni PD structures have been fabricated. This process has led to decrease in reverse bias dark current by ~ 10,000 times at 0V in comparison to the dark current values obtained for Ni/GaN/Ni MSM PDs. Photodetector parameters such as Photo-to-dark current ratio and Responsivity have increased from 8.8 and 0.004 A/W for Ni/GaN/Ni structures to 2.4×105 and 0.038 A/W for Ni/Zn-TPPOH/GaN/Zn-TPPOH/Ni structures, respectively at 0V. The spectral selectivity of the PDs has also improved at 0V, which means that the molecularly modified devices have become more responsive in UV spectral region and lesser in visible spectral region, if compared to bare-GaN based devices.
关键词： PDCR,Responsivity,Spectral selectivity
更新于2025-09-16 10:30:52
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Size-Dependent Photoresponse of Germanium Nanocrystals-Metal Oxide Semiconductor Photodetector
摘要： In this article, size-dependent photoresponse characteristics and low-frequency noise behavior of high-speed germanium nanocrystals (nc-Ge) photodetector have been reported. The nc-Ge embedded in SiO2 matrix with different sizes have been synthesized by annealing the cosputtered Ge-SiO2 thin films at 800 ?C–900 ?C. It has been observed that the photoresponse of the detector increases with the increasing size of nc-Ge. The sample annealed at 900 ?C showed maximum responsivity (3.5 A/W) with the fast response time. The low-frequency noise spectral power density in the current fluctuation (SI) have been measured for the fabricated nc-Ge photodetectors, and lowest noise equivalent power (NEP) and highest detectivity (D?) have been observed in the nc-Ge detector synthesized at 900 ?C. Tunable responsivity in nc-Ge has been observed due to size-dependent light absorption, electric field-driven carrier separation, and tunneling through the oxide barriers. The transient photoresponse behavior has also been studied and the best rise time of 6.2 μs was observed for nc-Ge synthesized at 900 ?C. These results suggest that the nc-Ge are a promising contender for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget.
关键词： Detectivity,noise equivalent power (NEP),responsivity,noise spectral power,germanium nanocrystals (nc-Ge)
更新于2025-09-16 10:30:52
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Heterostructures GaxIn1 –xAsyBizSb1 –y–z/InSb for Photodetector Devices
摘要： Isoparametric heterostructures GaxIn1 – xAsyBizSb1 – y – z/InSb for photodetectors operating in a 6- to 12-μ m wavelength interval have been manufactured by the method of floating-zone recrystallization with temperature gradient. The introduction of bismuth into GaInAsSb solid solution provides a decrease in bandgap width Eg, the corresponding increase in the working wavelength interval up to 12 μ m, and a shift in the photosensitivity maximum to longer wavelengths.
关键词： isoparametric heterostructures,photodetectors,IR detectors,absolute spectral sensitivity,volt–watt responsivity
更新于2025-09-16 10:30:52
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Au Grating on SiC Substrate: Simulation of High Performance Plasmonic Schottky Barrier Photodetector in Visible and NIR Regions
摘要： Plasmonically enhanced light absorption in Schottky barrier photodetectors (PDs) can be achieved by engineering metallic nanostructures. In this context, gold (Au) gratings on titanium (Ti)/silicon carbide (SiC) based Schottky barrier is proposed in this work for photodetection application. Further, the effects of various grating parameters and incident angle on absorbance are demonstrated. The grating based structure is able to provide ~85% incident light absorption leading to a significantly high responsivity value as compared with that of conventional (without metallic grating) structure. High unbiased responsivity values of 4.396 mA/W and 2.496 mA/W are obtained for Au/Ti/6H-SiC Schottky barrier PD at wavelengths of 694.5 nm and 1035 nm, respectively based on Fowler’s model. In view of advanced properties of SiC, the present work will open new opportunities for plasmonic PDs based on SiC platform.
关键词： plasmons,Schottky barrier,photodetector,responsivity,gold gratings
更新于2025-09-16 10:30:52
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Interfacea??Induced High Responsivity in Hybrid Graphene/GaAs Photodetector
摘要： Photodetectors based on two-dimensional (2D)/ three-dimensional (3D) semiconductor heterojunction structures are emerging as appealing candidates for high-sensitivity applications. The performances of these hybrid photodetectors are closely correlated with their current gain mechanism. Carrier recirculation is the most commonly reported mechanism. Recently, a Fermi level alignment mechanism was proposed for 2D graphene/0-dimensional (0D) quantum dot heterostructures because of the easy Fermi level tunability of the quantum dot. In this article, an interface-induced gain mechanism using this Fermi level alignment process is proposed and identified based on a 2D graphene/3D GaAs hybrid structure with comparative measurement configurations. Because of the high surface state density of GaAs, the photo-excited holes tend to become trapped at the graphene/GaAs interface, which can easily lower the interface Fermi level and the Fermi level in graphene via an alignment process. When combined with the high carrier mobility characteristics of graphene, a maximum current gain of 2520 and responsivity of 1321 A W?1 are achieved in the devices. This study clarifies the role of the interface states in the gain characteristics of some 2D/3D hybrid devices, with results that are instructive for optimal device design.
关键词： interface-induced gain,GaAs,responsivity,photodetectors,graphene
更新于2025-09-16 10:30:52
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Type-II superlattice photodetectors versus HgCdTe photodiodes
摘要： The development of the HgCdTe alloy as the most important intrinsic semiconductor for infrared (IR) technology is well established and recognized. In spite of the achievements in material and device quality, the drawbacks still exist due to bulk and surface instability, lower yields and higher costs particularly in fabrication of long wavelength infrared arrays. The dif?culties with this material encouraged to research on other compounds to improve device performance. Since the ?rst paper published by Sakaki and Esaki in 1978 it is well known that InAs and GaSb constitute a nearly lattice-matched material system offering great ?exibility in the design of IR optoelectronic devices. After four decades, the III-V type-II superlattice (T2SL) detector technology is under strong development as a possible alternative to HgCdTe. The novel ideas coming in design of detectors have enhanced the position of T2SLs in IR materials detector technology. It appears that T2SLs are especially helpful in the design of unipolar barriers. In this paper fundamental physical properties of two material systems, HgCdTe and T2SLs, are compared together with their in?uence on detector performance: dark current density, RA product, quantum ef?ciency, and noise equivalent different temperature. In comparison with HgCdTe, fundamental properties of T2SLs are inferior. On the other hand, T2SL and barrier detectors have several advantages to include lower tunnelling and surface leakage currents, and suppressed Auger recombination mechanism. Up to date, the promise of superior performance of these detectors has not been realized yet. In the paper we present that the performance of T2SL detectors (dark current, current responsivity, and noise equivalent difference temperature) is lower than bulk HgCdTe photodiodes. Due to stronger, less ionic chemical bonding of III-V semiconductors, these materials are attractive due to manufacturability and stability. It is also predicted that the interband T2SL quantum cascade devices will outperform the performance of the high operating temperature HgCdTe detectors.
关键词： Type-II superlattices,Responsivity,HgCdTe,Operability,Dark current,Interband cascade infrared detectors,Carrier lifetime
更新于2025-09-16 10:30:52
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Performance of polycrystalline GaN based metal-semiconductor-metal (MSM) photodetector with different contact
摘要： This paper describes performance of polycrystalline GaN based metal-semiconductor-metal (MSM) photodetector using different contact; Al, ITO, Ni and Pt. The performance of each photodetector was investigated in term of electrical resistivity (r ), signal-to-noise ratio (SNR), responsivity (R), internal quantum efficiency (η) and temporal responsivity. From the results, Ni is suggested to be a good contact for the photodetector. This is due to diffusion of NixO, formed by residual oxides on the GaN layer, into the Ni contact reduced the resistivity, thereby increasing the electrical conductivity of the photodetector. The photodetector with Ni contact demonstrated significant increase in SNR behavior with increasing bias voltage, while its r value was measured to be 2.02 M?.cm2, and η was 3.13%, 2.36% and 1.52%, at λ = 342 nm, 385 nm and 416 nm, respectively. From the temporal responsivity measurement, the rise time = 1.75 sec, the recovery time = 1.87 sec and the sensitivity = 5840%.
关键词： MSM photodetector,electrical contact,resistivity,internal quantum efficiency and temporal responsivity,signal-to-noise ratio,polycrystalline GaN,responsivity
更新于2025-09-12 10:27:22
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Optical Fiber Communications (Principles and Applications) || Optical Receivers
摘要： The purpose of a receiver in an electronic communication system is to extract the information sent by the corresponding transmitter with as minimum a carrier power level as possible. The primary function of an optical receiver in an optical fiber communication link is to convert the received optical signal into an equivalent electrical signal and recover the data. One of the main components of an optical receiver is a photodetector that converts incident optical signals into electric signals using photoelectric effects. High Sensitivity, dynamic range, fast response (i.e., acquisition time), high reliability, low noise, compatible size with that of fiber, and low cost are some of the important requirements of a photodetector. These requirements are best met by semiconductor photodetectors that convert an optical signal transmitted via optical fiber cables to equivalent electrical signals for further processing to achieve the desired output. The type of photodetectors suitable for three optical spectrum ranges of 800–900 nm, 900–1100 nm, and 1100–1600 nm vary in the material used for their fabrication as well as assembly techniques. A p–i–n photodiode is an ideal semiconductor photodetector device, because it can provide high quantum efficiency, fast response and capability to operate at higher modulation frequencies. The minimum received optical power that can be detected by a photodetector is limited by noise. A fully integrated single beam optical receiver comprises of a semiconductor photodiode, preamplifier in the electric domain, digital logic circuits, and an off-chip electronic driver circuit. This chapter discusses all the important aspects of photodetectors and optical receivers. The discussion begins with basic concepts behind the photo detection process, followed by description of different types of photodetectors usually used by optical receivers. Next, the components used in an optical receiver unit are explained. Finally, different types of noise sources in optical receivers that limit the signal-to-noise ratio, the receiver sensitivity parameter and its degradation are covered in sufficient detail.
关键词： Semiconductor Photodetectors,Noise Performance,Quantum Efficiency,Photodetectors,Avalanche Photodiode (APD),p–i–n Photodiode,Receiver Sensitivity,Responsivity,Optical Receivers
更新于2025-09-12 10:27:22