High Spectrum Selectivity Ultraviolet Photodetector Fabricated from an n-ZnO/p-GaN Heterojunction
26 Nov 2008-Journal of Physical Chemistry C (American Chemical Society)-Vol. 112, Iss: 51, pp 20546-20548
TL;DR: In this paper, undoped n-ZnO films have been deposited onto p-GaN to form a pn heterojunction, and the current−voltage curve of the heterjunction shows obvious rectifying behaviors.
Abstract: Undoped n-ZnO films have been deposited onto p-GaN to form a pn heterojunction, and the current−voltage curve of the heterojunction shows obvious rectifying behaviors. A photodetector is fabricated...
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TL;DR: A comprehensive review on the state-of-the-art research activities in the UV photodetection field, including not only semiconductor thin films, but also 1D nanostructured materials, which are attracting more and more attention in the detection field are provided.
Abstract: Ultraviolet (UV) photodetectors have drawn extensive attention owing to their applications in industrial, environmental and even biological fields. Compared to UV-enhanced Si photodetectors, a new generation of wide bandgap semiconductors, such as (Al, In) GaN, diamond, and SiC, have the advantages of high responsivity, high thermal stability, robust radiation hardness and high response speed. On the other hand, one-dimensional (1D) nanostructure semiconductors with a wide bandgap, such as β-Ga2O3, GaN, ZnO, or other metal-oxide nanostructures, also show their potential for high-efficiency UV photodetection. In some cases such as flame detection, high-temperature thermally stable detectors with high performance are required. This article provides a comprehensive review on the state-of-the-art research activities in the UV photodetection field, including not only semiconductor thin films, but also 1D nanostructured materials, which are attracting more and more attention in the detection field. A special focus is given on the thermal stability of the developed devices, which is one of the key characteristics for the real applications.
650 citations
Cites background from "High Spectrum Selectivity Ultraviol..."
...The n-ZnO films had been deposited onto p-GaN to form a p-n junction, and the I-V curves showed obvious rectifying behaviors [136]....
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TL;DR: In this paper, the authors focused on the perspective of molding devices through exploring new materials and novel architectures inspired by state-of-the-art UV photodetectors.
594 citations
TL;DR: The performance of ZnO-based photodetectors is analyzed, discussing recent achievements, and comparing the characteristics of the variousPhotodetector structures developed to date.
Abstract: Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one of the most promising candidates for UV photodetectors. Additionally, doping in ZnO with Mg elements can adjust the bandgap largely and make it feasible to prepare UV photodetectors with different cut-off wavelengths. ZnO-based photoconductors, Schottky photodiodes, metal–semiconductor–metal photodiodes and p–n junction photodetectors have been developed. In this work, it mainly focuses on the ZnO and ZnMgO films photodetectors. We analyze the performance of ZnO-based photodetectors, discussing recent achievements, and comparing the characteristics of the various photodetector structures developed to date.
558 citations
Cites background or methods from "High Spectrum Selectivity Ultraviol..."
...After that, Nakano et al. demonstrated the Schottky photodiodes consisting of a MgxZn1-xO (x ≤ 0.43) thin film and a transparent conducting polymer, poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) by MBE [103]....
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...In order to realize visible blind UV photodetectors, Zhang et al. have fabricated a photodetector based on a double heterojunction of n-ZnO/insulator-MgO/ p-Si grown by MBE [65]....
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...All these results indicate that RF sputtering, PLD, MBE and MOCVD are very suitable methods to fabricate ZnO-based UV photodetectors, especially for ZnMgO solar-blind photodetectors....
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...Sensors 2010, 10 8623 Joike et al. have fabricated single-phase wurtzite Zn1-xMgxO alloy films with 0 < x < 0.45 on (111)-oriented Si substrates by MBE [97]....
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...8O/n-ZnO heterojunction ultraviolet photodiode on a sapphire substrate by MBE [96]....
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TL;DR: Ultrafast-response (20 μs) UV detectors, which are visible-blind and self-powered, in devices where an n-type ZnO nanowire partially lies on a p-type GaN film, are demonstrated.
Abstract: Ultrafast-response (20 μs) UV detectors, which are visible-blind and self-powered, in devices where an n-type ZnO nanowire partially lies on a p-type GaN film, are demonstrated. Moreover, a CdSe-nanowire red-light detector powered by a nanoscale ZnO/GaN photovoltaic cell is also demonstrated, which extends the device function to a selective multiwavelength photodetector and shows the function of an optical logical AND gate.
354 citations
TL;DR: A comprehensive summary of the recent progress mainly on photodetectors based on inorganic p-type semiconductor materials is presented.
Abstract: Photoelectric detectors are the central part of modern photodetection systems with numerous commercial and scientific applications. p-Type semiconductor materials play important roles in optoelectronic devices. Photodetectors based on p-type semiconductor materials have attracted a great deal of attention in recent years because of their unique properties. Here, a comprehensive summary of the recent progress mainly on photodetectors based on inorganic p-type semiconductor materials is presented. Various structures, including photoconductors, phototransistors, homojunctions, heterojunctions, p-i-n junctions, and metal-semiconductor junctions of photodetectors based on inorganic p-type semiconductor materials, are discussed and summarized. Perspectives and an outlook, highlighting the promising future directions of this research field, are also given.
290 citations
References
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TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...
10,260 citations
TL;DR: In this paper, the results of Schottky UV photodetectors fabricated on n-type ZnO epitaxial films were presented, which were grown on R-plane sapphire substrates by metalorganic chemical vapor deposition.
889 citations
Book•
28 Aug 2000
TL;DR: The second edition of The Blue Laser Diode as discussed by the authors has been published and is available for a modest $39 (about £15) in the UK and can be used as a reference for a number of applications.
Abstract: The story of Shuji Nakamura and the blue laser diode is remarkable. It is clear from this book that he enjoys this fact and wishes his readers to become familiar with his success. Nakamura was a little known researcher at a small but successful Japanese company, Nichia Chemical, on Shikoku, one of Japan's four main islands. One of their successful lines was phosphors for fluorescent lights. In 1989, Nakamura was given a few million dollars by the company's Chairman Nobuo Ogawa. Nakamura chose to research into blue light emitters using gallium nitride, a material that had been studied by Pankove at RCA some 20 years earlier and largely written off by the conventional semiconductor industry. In spite of many factors against progress, this second edition of The Blue Laser Diode testifies to the success of this gamble. The book is subtitled `The complete story'. This is an unlikely epithet for the book because there is still a long way to go. The book is written with a mixture of academic integrity and commercial trumpet blowing. There is too often a lack of detail and logical order. There is inadequate discussion of the case for and against other materials such as ZnSe. One feels that the commercial pressure not to give away all the answers about gallium nitride has triumphed over the wish for scientific disclosure to enable results to be repeated. The book clearly reports the two most significant difficulties faced by gallium nitride. First, it appeared from Pankove's work that it would not to be easy to find an appropriate p-type dopant that could make suitable p-n junctions. Two chapters consider this problem, starting with low energy electron beam irradiation and then in the second chapter considering thermal annealing in nitrogen. The writing and detail suggest that it is still a technology rather than science (or, perhaps more unkindly, cook-book recipes of time and temperature). The second important difficulty is that gallium nitride has too many dislocations for long-life laser action. Growth on sapphire with appropriate buffer layers is described as an initial step in reducing the dislocations. Later in the book, it is recognized that InxGa1-xN offers greater versatility, and this is considered in more detail along with InGaN/AlGaN double heterostructures. Regrettably it is not easy though to dig out from this book all the details of lattice matching that are required and how successful lattice matching has been in removing dislocations and increasing lifetime. Clearly the general trend of longer lifetimes means that there has been useful success. Blue laser diodes are now claimed to be commercially available with lifetimes measured in thousands of hours while blue light emitting diodes, with their lower current densities, are said to have lifetimes measurable in years. The book has a little for everyone. Applications are noted briefly as well as blow-by-blow accounts of the manufacturing technology of double heterostructure, multi-quantum well lasers and progress to room temperature operation. Applications range from the mundane traffic light, through full colour displays to 15-20 Gbyte optically read data storage discs. Interestingly it is the mundane applications that may have the biggest financial impact. A statistic that appears on the Internet is that if all the traffic signals in Japan could be switched to suitable LEDs then one could save the construction of at least one nuclear power plant. Although Nakamura is an admirer of Pankove's work, the writing and scientific style does not match that of Pankove. Nevertheless the book records a thorough solid achievement and as such there should be a similar solid basis for many readers in materials science and laser technology wishing to read this book. The book regrettably gives no indication why Nakamura has left Nichia for a Professorship at Santa Barbara after such magnificent early support by Nichia. Nor does the book explain why Nakamura's co-author Gerhard Fasol is undercutting the joint venture by selling for $15 over the web a 28 page summary about blue laser diodes using gallium nitride. However, if price is no consideration, there is also advertised on the web a 222 page report SC-23 from Strategies Unlimited entitled `Gallium Nitride 2000 - Technology Status, Applications, and Market Forecast' for a modest $3950. Clearly the present book cannot be `the complete story'. That will run for quite a time yet. John Carroll
683 citations
TL;DR: In this paper, the absorption coefficient for a 0.4-μm-thick GaN layer grown on a polished sapphire substrate was determined from transmission measurements at room temperature.
Abstract: The absorption coefficient for a 0.4-μm-thick GaN layer grown on a polished sapphire substrate was determined from transmission measurements at room temperature. A strong, well defined exciton peak for the A and B excitons was obtained. The A, B, and C excitonic features are clearly defined at 77 K. At room temperature, an energy gap Eg=3.452±0.001 eV and an exciton binding energy ExA,B=20.4±0.5 meV for the A and B excitons and ExC=23.5±0.5 meV for the C exciton were determined by analysis of the absorption coefficient. From this measured absorption coefficient, together with the detailed balance approach of van Roosbroek and Shockley, the radiative constant B=1.1×10−8 cm3/s was obtained.
665 citations
TL;DR: In this paper, the photoelectric properties of n-ZnO/p-Si photodiodes were investigated for detecting UV and visible photons in the depleted ZnO and p-Si, respectively.
Abstract: We report on the photoelectric properties of n-ZnO/p-Si photodiodes which detect UV photons in the depleted n-ZnO and simultaneously detect visible photons in the depleted p-Si. As characterized by I–V measurements in the photon range of 310 to 650 nm our photodiodes exposed to UV photons show a linear increase in photocurrent with reverse bias. In the visible range, the photocurrent rises rapidly with bias but saturates beyond a critical voltage. Our diodes exhibit strong responsivities of 0.5 and 0.3 A/W for UV (310-nm) and red (650-nm) photons, respectively, under a 30-V bias with a weak minimum near 380 nm, the wavelength corresponding to the band gap of ZnO. It is concluded that our n-ZnO/p-Si diode can be a UV-enhanced photodiode that simultaneously detects UV and visible photons by employing two related photoelectric mechanisms in parallel.
381 citations