Catalyst-free direct growth of InP quantum dots on Si by MOCVD: a step toward monolithic integration
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RESEARCH PAPER
Catalyst-free direct growth of InP quantum dots on Si by MOCVD: a step toward monolithic integration Nripendra N. Halder • Souvik Kundu • Rabibrata Mukherjee • D. Biswas • P. Banerji
Received: 9 June 2012 / Accepted: 31 October 2012 / Published online: 15 November 2012 Springer Science+Business Media Dordrecht 2012
Abstract InP quantum dots (QDs) were grown on catalyst-free Si substrates by MOCVD to study the behavior of growth of low dimensional III–V structures on Si substrates. It is found that at temperature 575 C, uniform QDs with diameter 20–50 nm and height 6–8 nm were obtained, whereas at 600 C, InP nanoislands with wetting layers were formed instead of QDs. From the photoluminescence measurements, blue shift of the band gap is observed with a value of 1.395 eV. The densities of the QDs were found to be 7–8 9 1013 m-2. X-ray photoelectron spectroscopy establishes the presence of InP rather than indium droplet. X-ray diffraction spectra show different surface planes of the QDs. The effect of growth temperature has been discussed. N. N. Halder Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India S. Kundu P. Banerji (&) Materials Science Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India e-mail: [email protected] R. Mukherjee Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India D. Biswas Department of Electronics & Electrical Communication Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
Keywords Quantum dots MOCVD Indium phosphide Volmer–Weber growth Photoluminescence
Introduction The availability of a large-diameter wafer and matured processing technology provides Si a tremendous benefit over III–V semiconductor. As Si is an indirect band gap semiconductor and also a very poor emitter of light, III–V hybrid integration on Si is the primary requirement for fabricating optoelectronic devices. On-chip optical interlinks are needed for next generation affordable, high functioning, and high throughput computing systems since relative to the mainstream metal interlinks, they have some edges such as their ultralow power dissipation, low response time, and high bandwidth (Ayers 2007; Lockwood 2009; Mi et al. 2009). Epitaxy of III–V polar semiconductors, specially InP on non-polar Si substrate, is elusive due to large lattice mismatch of 8.1 % and large thermal expansion coefficient variation of 76.9 %, resulting in large dislocations (108–1010 cm-2) in the grown epitaxial film (Liang and Bowers 2010; Bietti et al. 2010) with rapid degradation of the electronic behavior of the devices. However, it is found from the literature that low dimensional structures, say quantum dots, can be grown on Si with less numbers of dislocations owing to the quantization of
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carriers in the dots (Zundel et al. 1999). InP has distinct edges over other III–V materials such as its carrier multiplication ability as found re
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