Visible-blind photodetector based on p-i-n junction GaN nanowire ensembles
ABSTRACT We report the synthesis, fabrication and extensive characterization of a visible-blind photodetector based on p-i-n junction GaN nanowire ensembles. The nanowires were grown by plasma-assisted molecular beam epitaxy on an n-doped Si(111) substrate, encapsulated into a spin-on-glass and processed using dry etching and metallization techniques. The detector presents a high peak responsivity of 0.47 A W(-1) at - 1 V. The spectral response of the detector is restricted to the UV range with a UV-to-visible rejection ratio of 2 x 10(2). The dependence on the incident power and the operation speed of the photodetector are discussed.
Full-textDOI: · Available from: Andres De Luna Bugallo, Mar 26, 2014
SourceAvailable from: Lorenzo Rigutti
Chapter: Semiconductor Nanowires[Show abstract] [Hide abstract]
ABSTRACT: Semiconductor nanowires are cylindrical semiconducting crystals having a diameter d of the order of 100 nm or lower and a high (>∼10) length over diameter aspect ratio. They have been demonstrated in many different materials systems and constitute a various and dynamical research field in the framework of solid-state physics, nanoscience, and nanotechnology. Their interest resides both in their peculiar fundamental properties and in the possibility of developing original nanoscale devices. This article will introduce and review the synthesis methods for bottom-up semiconductor nanowires. Then, their specific properties will be addressed. A third section is specifically dedicated to discussing the technological approaches for the realization of nanowire devices and to different device applications.Wiley Encyclopedia of Electrical ane Electronic Engineering, Edited by John Webster, 09/2014: pages 1-33; Wiley.
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ABSTRACT: This paper presents an investigation of photoelectric properties of the CVD-grown multi-prong GaN nanowires. The multi-prong growth mechanism produces uniform high density long GaN nanowires, which is very significant for scale-up manufacturing opportunities. Photoelectric studies of the GaN nanowires have been conducted at various light sources with wavelengths of 254 nm and 365 nm. The 254 nm-light exposure resulted in a larger photocurrent increase compared to that of 365 nm-light exposure, which is attributed to the larger number of the photogenerated carriers owing to the higher photon energy. The positive photoelectric response of the GaN nanowires is attributed to the molecular sensitization mechanism. Furthermore, the GaN nanowires devices exhibited moderate persistent photocurrent. These findings suggest a reduced surface recombination process due to the depletion surface charge layer. In summary, the multi-prong GaN nanowires could be utilized as photoconductors, photodetectors, and various photosensing elements in many highly integrated optoelectronic devices.Sensors and Actuators A Physical 09/2014; 216:142-146. DOI:10.1016/j.sna.2014.05.028 · 1.94 Impact Factor
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ABSTRACT: Nonpolar a-axial GaN nanowire (NW) was firstly used to construct the MSM (metal-semiconductor-metal) symmetrical Schottky contact device for application as visible-blind Ultraviolet (UV) detector. Without any surface or composition modification, the fabricated device demonstrated a superior performance through a combination of its high sensitivity (up to 104 A/W) and EQE value (up to 105) as well as ultrafast (＜26 ms) response speed, which indicates a balance between the photocurrent gain and the response speed has been achieved. Based on its excellent photoresponse performance, an optical logic AND gate and OR gate have been demonstrated for performing photo-electronic coupled logic devices by further integrating the fabricated GaN NW detectors, which logically convert optical signals to electrical signals in real time. These indicate the possibility of using nonpolar GaN NW not only as a high performance UV detector, but also as a stable optical logic device, in light-wave communications and for future memory storage.Nanoscale 08/2014; 6(20). DOI:10.1039/C4NR03581J · 6.74 Impact Factor