Pulsed laser deposition of uniform semiconductor nanodot arrays
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Pulsed laser deposition of uniform semiconductor nanodot arrays Manisha Gupta · Vincent Sauer · Ying Yin Tsui
Received: 20 May 2011 / Accepted: 3 August 2012 / Published online: 24 August 2012 © Springer-Verlag 2012
Abstract Uniform arrays of silicon (Si), gallium arsenide (GaAs) and zinc oxide (ZnO) nanodots have been deposited using Pulsed Laser Deposition (PLD) technique combined with a contact mask consisting of nano-holes fabricated by E-beam lithography (EBL). These nanocrystalline semiconductor nanodots have been deposited by PLD on Si and GaAs substrates at room temperature. Characterization of the nanodots has been carried out using different techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Auger Electron Spectroscopy (AES), and Raman spectroscopy. This work demonstrates a novel technique for deposition of uniform array of semiconductor nanostructures using a contact mask at room temperature for photonic applications.
1 Introduction Semiconductor nanodots have various applications including solar cells [1], photonics devices [2, 3], transistors [4], and sensor applications [5] to name a few. Pulsed laser deposition (PLD) is a versatile technique for growing different materials on a variety of substrates [6, 7]. PLD is a wellestablished technique for maintaining material stoichiometry and can be used to grow complex material systems [6, 7]. M. Gupta () · V. Sauer · Y.Y. Tsui Department of Electrical & Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada e-mail: [email protected] Fax: +1-780-4921811 V. Sauer National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
It is also capable of producing thin films consisting of nanostructures, including nanodots [2–4, 8]. We have been studying different semiconductor material nanodots grown by PLD. Silicon (Si), gallium arsenide (GaAs), and zinc oxide (ZnO) nanodots were deposited using PLD on GaAs and Si substrates. In our earlier work, we have studied self-assembled semiconductor nanodots using nanosecond (ns) and femtosecond (fs) PLD [8]. The selfassembled nanodots vary in size and spacing. In addition, micron size droplets and debris are also present. Many applications including photonic devices, solar cell applications, etc. require uniformly sized and spaced patterns of nanostructures. To create semiconductor nanodots in arrays with uniform size and spacing, PLD was used in a lift-off technique with nano-holes patterned in a polymer mask by electron beam lithography (EBL). In this paper, we report the details of the fabrication technique and characteristics of the GaAs nanodots.
2 Experimental technique All the PLD growths were conducted using a 248 nm, 15 ns, 12 Hz KrF laser in a vacuum chamber with a base vacuum of 1 × 10−5 mbar. The laser was incident at 45 degrees to the target. Optimal fluence and growth conditions were established by growing bulk films of each material. These conditions were then employed to deposit nanodots usi
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