Miao and Zhang Nanoscale Research Letters 2012, 7:321 http://www.nanoscalereslett.com/content/7/1/321 N A N O E X P R E S S Open Access Stages in the catalyst-free InP nanowire growth on silicon (100) by metal organic chemical vapor deposition Guoqing Miao* and Dengwei Zhang Abstract Catalyst-free InP nanowires were grown on Si (100) substrates by low-pressure metal organic chemical vapor deposition. The different stages of nanowire growth were investigated. The scanning electron microscopy images showed that the density of the nanowires increased as the growth continued. Catalyzing indium droplets could still be fabricated in the nanowire growing process. X-ray diffraction showed that the nanowires grown at different stages were single crystalline with <111 > growth direction. The photoluminescence studies carried out at room temperature on InP nanowires reveal that the blueshift of photoluminescence decreased as the growing time accumulates, which is related to the increase in the diameter, rather than the length. Raman spectra for nanowires at different growing stages show that the quality of the nanowire changes. The growth of InP nanowires at different growing stages is demonstrated as a dynamic process. Keywords: InP, nanowire, catalyst-free growth, MOCVD, photoluminescence, Raman Background Semiconductor nanowires of different materials have received increasing attention in recent years for their nanodevice application as one-dimensional structures and building blocks [1-6]. III-V nanowires grown on Si substrate have superior electronic properties of direct- bandgap III-V materials combined with the low cost and well-known properties of silicon. One way of fabricating III-V nanowires is by vapor–liquid–solid (VLS) method [7] using metal organic chemical vapor deposition (MOCVD) [8]. In the typical fabrication of III-V semi- conductor nanowires by the VLS method, gold nanopar- ticle has been used as catalyst [9]. However, gold nanoparticle-mediated growth produces unwanted effects in nanowires, such as introduction of deep levels [10] and gold migration [11] on the semiconductor sur- face. In order to avoid these impacts, catalyst-free growth is demonstrated by using in situ deposited in- dium droplets as seeds for nanowire growth [12]. * Correspondence: miaogq@ciomp.ac.cn State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, People’s Republic of China Catalyst-free InP nanowire growth has been realized by MOCVD, and the influence of different growing con- ditions has been discussed [13]. Vertical InP nanowires have been grown on Si (111) using indium droplets as the catalysts [14]. Individual bulk-like wires of wurtzite InP have been investigated by photoluminescence, photoluminescence excitation spectroscopy, and trans- mission electron microscopy [15]. Size-dependent photoluminescence from single indium phosphide nano- wires has been discussed [16]. If production of nano- wires is to reach a technologically relevant scale, exact control of the structure is necessary, and this entails a greater understanding and control of the growth process. In this paper, we study the entire forest of InP nanowires at different growing stages during the MOCVD growth process for a single set of growth conditions. In the fol- lowing, we first present that new nanowires could grow in a catalyst-free InP nanowire growing process. We then proceed to describe the nanowires during different stages of the growth process by X-ray diffraction. Finally, we identify that the photoluminescence (PL) of the nanowires has direct relations with the diameter and the crystal quality of InP nanowires at different growing stage changes. © 2012 Miao and Zhang et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.