Si-Based ZnO Ultraviolet Photodiodes
19 Dec 2012-
TL;DR: Semiconductor-based ultraviolet photodiodes have been continuously developed that can be widely used in various commercial, civilian areas, and military applications, such as optical communications, missile launching detection, flame detection, UV radiation calibra- tion and monitoring, chemical and biological analysis, optical communications and astro- nomical studies, etc as mentioned in this paper.
Abstract: Semiconductor-based ultraviolet (UV) photodiodes have been continuously developed that can be widely used in various commercial, civilian areas, and military applications, such as optical communications, missile launching detection, flame detection, UV radiation calibra‐ tion and monitoring, chemical and biological analysis, optical communications, and astro‐ nomical studies, etc. [1-2]. All these applications require very sensitive devices with high responsivity, fast response time, and good signal-to-noise ratio is common desirable charac‐ teristics. Currently, light detection in the UV spectral range still uses Si-based optical photo‐ diodes. Due to the Si-based photodiodes are sensitive to visible and infrared radiation, the responsivity in the UV region is still low [3-5]. To avoid these disadvantages, wide-bandgap materials (such as diamond, SiC, III-nitrides and wide-bandgap II–VI materials) are under intensive studies to improve the responsivity and stability of UV photodiodes, because of their intrinsic visible-blindness [6].
Citations
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TL;DR: The history of bipolar oxide thin film devices can be found in this article, where a wide range of n-type and p-type oxides has been explored for the formation of such bipolar diodes.
Abstract: We present the history of, and the latest progress in, the field of bipolar oxide thin film devices. As such we consider primarily pn-junctions in which at least one of the materials is a metal oxide semiconductor. A wide range of n-type and p-type oxides has been explored for the formation of such bipolar diodes. Since most oxide semiconductors are unipolar, challenges and opportunities exist with regard to the formation of heterojunction diodes and band lineups. Recently, various approaches have led to devices with high rectification, namely p-type ZnCo2O4 and NiO on n-type ZnO and amorphous zinc-tin-oxide. Subsequent bipolar devices and applications such as photodetectors, solar cells, junction field-effect transistors and integrated circuits like inverters and ring oscillators are discussed. The tremendous progress shows that bipolar oxide electronics has evolved from the exploration of various materials and heterostructures to the demonstration of functioning integrated circuits. Therefore a viable, facile and high performance technology is ready for further exploitation and performance optimization.
83 citations
TL;DR: In this article, the fabrication and characterization of ZnO-based UV photodiodes with p-NiO as an intermediate electron blocking layer (EBL) was reported.
Abstract: We report the fabrication and characterization of ZnO-based UV photodiodes with p-NiO as an intermediate electron blocking layer (EBL). The n-ZnO and p-ZnO layers are deposited by automated spray pyrolysis technique and NiO layers by r.f.magnetron sputtering. For the realization of p-ZnO, dual acceptor method has been adopted by doping equimolar concentration of group-V elements P and N (0.75 at%) simultaneously in ZnO. The formation of p-type characteristics in ZnO is confirmed by Hall measurement and X-ray photoelectron spectroscopy (XPS) analysis. The n-ZnO is doped with Al (3 at%) in order to improve the electrical properties. The properties of sputtered NiO layers have been investigated under three different deposition temperatures of 300 °C, 350 °C and 400 °C. By analyzing structural and electrical properties, it is revealed that NiO deposited at 350 °C possess better crystallinity and electrical properties. The optimum p-ZnO and n-ZnO layers are stacked upon ITO substrates to form ZnO-based p-n junctions. The effect of addition of NiO as an electron blocking layer (EBL) between the p-n junctions is investigated by analyzing the current density-voltage (J-V) and UV photoresponse properties. The fabricated ZnO-based UV photodiodes with NiO EBL exhibits a high photoresponsivity (R) value of 5.53 A/W with external quantum efficiency (EQE) value of 1.87 × 103%.
28 citations
TL;DR: In this article, a simulation study and performance analysis of ZnO/Si heterojunction-based UV-visible photodetector is presented, where different electrical and optical parameters such as energy band diagram, electric field profile, dark current, quantum efficiency, responsivity, detectivity, and noise equivalent power are simulated as a function of device thickness, operating wavelength, and applied reverse bias voltage.
Abstract: This article reports simulation study and performance analysis of ZnO/Si heterojunction-based UV–visible photodetector. Different electrical and optical parameters such as energy band diagram, electric field profile, dark current, quantum efficiency, responsivity, detectivity, and noise equivalent power of ZnO/Si heterojunction-based photodetector have been simulated as a function of device thickness, operating wavelength, and applied reverse bias voltage. The simulation software ATLAS™ in SILVACO package is used to describe the effect of ZnO/Si interface properties on its photodetection. The value obtained for external quantum efficiency, responsivity, and specific detectivity for ZnO/Si heterojunction-based photodetector were ∼93%, 0.36 A/W, and 7.2 × 1010 cm Hz½ W−1, respectively. The estimated values for dark current and noise equivalent power were of the order of 10−14 A and 10−11 W, respectively.
17 citations
TL;DR: In this paper, the effect of optoelectrical properties of CdO:Ge film on the constructed p-n heterojunction, as well as to study the dependence of the optosensitivity and optoresponse of the heterjunction on the Ge% doping level was studied.
Abstract: The electrical properties of Ge-doped CdO (CdO:Ge) films grown on p-Si were studied in this work. The focussing was on the effect of optoelectrical properties of CdO:Ge film on the optoelectrical properties of the constructed p–n heterojunction, as well as to study the dependence of the optosensitivity and optoresponse of the heterojunction on the Ge% doping level. The characterisation of the transparent conducting oxide CdO:Ge layer was performed by the X-ray diffraction, SEM, electrical measurements, and spectral photometry. A strong optosensitivity was found especially for the p–n heterojunction that used 0.16 wt% Ge-doped CdO, attaining a great value of about 60,000% comparing to undoped CdO. In addition, a good value of optical response of 319.4 mA/W for the p–n heterojunction constructed with 0.25 wt% Ge-doped CdO. The results show that CdO:Ge/p-Si heterojunctions act as very good candidates for constructing high-efficiency photodetectors.
13 citations
Additional excerpts
...204 A/W for 530 nm [29]....
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TL;DR: In this article, a vertically aligned and electrically conducting n-type Al (3.75 µm) doped ZnO nanowires were grown by a simple aqueous chemical growth process.
Abstract: Ultraviolet (UV) photodiodes with fast photoresponse properties were fabricated using vertically aligned aluminum doped ZnO nanowires. Stable p-type ZnO have been achieved by doping equimolar concentration of P-N (0.75 at.%) simultaneously in ZnO. The vertically aligned and electrically conducting n-type Al (3 at.%) doped ZnO nanowires were grown by a simple aqueous chemical growth process. The structural, morphological, optical, and electrical properties were investigated. For the fabrication of UV photodiodes, the optimum p-type ZnO layers and n-type ZnO nanowires were stacked upon ITO substrate. A 250 nm thin NiO was deposited as an electron blocking layer (EBL) in between the ZnO p–n junctions. The current density–voltage (J–V) characteristic of the fabricated UV photodiode was measured under dark and UV illumination conditions. Under a reverse bias of 3 V, the device exhibits a high photoresponsivity (R) value of 15.07 (A/W) upon illumination of UV light (λ = 365 nm). The fabricated photodiode exhibits a fast photoresponse switching characteristics with a response and recovery time calculated as 61 ± 11 and 455 ± 41 ms, respectively. The role of vertically aligned nanowires in the formation of oxygen interstitial (Oi) defects and its impact on improving the UV photoresponse properties were investigated.
11 citations
Cites background or methods from "Si-Based ZnO Ultraviolet Photodiode..."
...When the AZO15 nanowire UV photodiode is irradiated with UV light (365 nm), the valence electrons get excited and results in the formation of eh pairs in the depletion region [59, 60]....
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...The EQE of AZO15 nanowire UV photodiodes was calculated using the following relation [12, 59],...
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...The photoresponsivity (R) of the fabricated photodiode is defined as ratio of photocurrent to the power of input UV light and calculated using the following relation [12, 59],...
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...The detectivity or the detection capability (D) is defined as the measure of the least detectable radiant power and calculated using the following relation [12, 59],...
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References
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TL;DR: Zener's model of ferromagnetism, originally proposed for transition metals in 1950, can explain T(C) of Ga(1-)(x)Mn(x)As and that of its II-VI counterpart Zn(1)-Mn (x)Te and is used to predict materials with T (C) exceeding room temperature, an important step toward semiconductor electronics that use both charge and spin.
Abstract: Ferromagnetism in manganese compound semiconductors not only opens prospects for tailoring magnetic and spin-related phenomena in semiconductors with a precision specific to III-V compounds but also addresses a question about the origin of the magnetic interactions that lead to a Curie temperature (T(C)) as high as 110 K for a manganese concentration of just 5%. Zener's model of ferromagnetism, originally proposed for transition metals in 1950, can explain T(C) of Ga(1-)(x)Mn(x)As and that of its II-VI counterpart Zn(1-)(x)Mn(x)Te and is used to predict materials with T(C) exceeding room temperature, an important step toward semiconductor electronics that use both charge and spin.
7,062 citations
"Si-Based ZnO Ultraviolet Photodiode..." refers background in this paper
...als, doped with transition metal (TM) ions, is also expected to have applications in spintronics, including in information storage and data-processing devices [56]....
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TL;DR: Despite the slow relaxation time, the extremely high internal gain of ZnO NW photodetectors results in gain-bandwidth products higher than approximately 10 GHz, which promise a new generation of phototransistors for applications such as sensing, imaging, and intrachip optical interconnects.
Abstract: ZnO nanowire (NW) visible-blind UV photodetectors with internal photoconductive gain as high as G ∼ 108 have been fabricated and characterized. The photoconduction mechanism in these devices has been elucidated by means of time-resolved measurements spanning a wide temporal domain, from 10-9 to 102 s, revealing the coexistence of fast (τ ∼ 20 ns) and slow (τ ∼ 10 s) components of the carrier relaxation dynamics. The extremely high photoconductive gain is attributed to the presence of oxygen-related hole-trap states at the NW surface, which prevents charge-carrier recombination and prolongs the photocarrier lifetime, as evidenced by the sensitivity of the photocurrrent to ambient conditions. Surprisingly, this mechanism appears to be effective even at the shortest time scale investigated of t < 1 ns. Despite the slow relaxation time, the extremely high internal gain of ZnO NW photodetectors results in gain-bandwidth products (GB) higher than ∼10 GHz. The high gain and low power consumption of NW photodetec...
2,448 citations
"Si-Based ZnO Ultraviolet Photodiode..." refers background in this paper
...In addition, the en‐ hanced UV photoconductive response in ZnO NWs may be attributed to the presence of oxygenrelated hole-trap states at the NW surface [29]....
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...It appears that the ZnO surface can be depleted by the surface oxygen absorption according to the hole-trapping mechanism [29]....
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TL;DR: By applying electric fields, the ability to externally control the properties of magnetic materials would be highly desirable from fundamental and technological viewpoints is demonstrated, particularly in view of recent developments in magnetoelectronics and spintronics.
Abstract: It is often assumed that it is not possible to alter the properties of magnetic materials once they have been prepared and put into use. For example, although magnetic materials are used in information technology to store trillions of bits (in the form of magnetization directions established by applying external magnetic fields), the properties of the magnetic medium itself remain unchanged on magnetization reversal. The ability to externally control the properties of magnetic materials would be highly desirable from fundamental and technological viewpoints, particularly in view of recent developments in magnetoelectronics and spintronics. In semiconductors, the conductivity can be varied by applying an electric field, but the electrical manipulation of magnetism has proved elusive. Here we demonstrate electric-field control of ferromagnetism in a thin-film semiconducting alloy, using an insulating-gate field-effect transistor structure. By applying electric fields, we are able to vary isothermally and reversibly the transition temperature of hole-induced ferromagnetism.
1,879 citations
"Si-Based ZnO Ultraviolet Photodiode..." refers background in this paper
...The electron‐ ic, optical and magnetic properties of TM-doped ZnO and related materials have been stud‐ ied extensively [57-64]....
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TL;DR: In this paper, a general review of the advances in widebandgap semiconductor photodetectors is presented, including SiC, diamond, III-nitrides and ZnS.
Abstract: Industries such as the automotive, aerospace or military, as well as environmental and biological research have promoted the development of ultraviolet (UV) photodetectors capable of operating at high temperatures and in hostile environments. UV-enhanced Si photodiodes are hence giving way to a new generation of UV detectors fabricated from wide-bandgap semiconductors, such as SiC, diamond, III-nitrides, ZnS, ZnO, or ZnSe. This paper provides a general review of latest progresses in wide-bandgap semiconductor photodetectors.
1,194 citations
TL;DR: In this paper, a review of recent results in developing improved fabrication processes for ZnO devices with the possible application to UV light emitters, spin functional devices, gas sensors, transparent electronics, and surface acoustic wave devices is given.
Abstract: A review is given of recent results in developing improved fabrication processes for ZnO devices with the possible application to UV light emitters, spin functional devices, gas sensors, transparent electronics, and surface acoustic wave devices. There is also interest in integrating ZnO with other wide band-gap semiconductors, such as the AlInGaN system. In this article, we summarize recent progress in controlling n- and p-type doping, materials processing methods, such as ion implantation for doping or isolation, Ohmic and Schottky contact formation, plasma etching, the role of hydrogen in the background n-type conductivity of many ZnO films, and finally, the recent achievement of room-temperature ferromagnetism in transition-metal (Mn or Co)-doped ZnO. This may lead to another class of spintronic devices, in which the spin of the carriers is exploited rather than the charge as in more conventional structures.
656 citations
"Si-Based ZnO Ultraviolet Photodiode..." refers background in this paper
...Among them, zinc oxide (ZnO) is another wide direct bandgap material due to its sensitive and UV photoresponse in the UV region [7-9]....
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