The Benefits of HCl in the Growth of Silicon Nanowires by Chemical Vapour Deposition: Growth of Small Diameter Nanowires
- PDF / 448,762 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 26 Downloads / 205 Views
1258-P05-06
The Benefits of HCl in the Growth of Silicon Nanowires by Chemical Vapour Deposition: Growth of Small Diameter Nanowires and Controlled Facet Evolution. Fabrice Oehler1, Pascal Gentile1, Thierry Baron2 and Pierre Ferret3 1
CEA, INAC/SP2M, Laboratoire SiNaPS, 17 Rue des Martyrs, F-38054 Grenoble, France LTM/CNRS/UJF/Grenoble-INP, 17 Rue des Martyrs, F-38054 Grenoble, France 3 CEA Leti MINATEC, 17 Rue des Martyrs, F-38054 Grenoble Cedex 9, France 2
ABSTRACT The effects of hydrogen chloride (HCl) on the growth of silicon nanowires by Chemical Vapour Deposition are investigated. HCl is found to enable the growth of small diameter gold-catalyzed silicon nanowires while reducing the kink occurrence. Specific growth sequences are presented in order to obtain a one-to-one ratio of nanowire growth versus gold colloidal seed. Other growth sequences using HCl are illustrated but achieve mixed results concerning the nanowire structure and the surface state. INTRODUCTION During the past ten years, semiconducting nanowires have been the subject of intensive research projects for the future 1D electronic[1] or the next generation of solar cells[2]. However to succeed as the cornerstone of high frequency FET or multi-jonctions cells, the dimensions and the electronic properties of the wires must be tightly controlled. Kayes et al.[3] reported the growth of impressive arrays of silicon nanowires (SiNWs) by Chemical Vapour Deposition (CVD) from patterned substrate using tetrachlorosilane (SiCl4), while Schmid et al.[4] showed that control of the growth direction was not straight forward using silane (SiH4). This divergence of results obtained either with SiCl4 or SiH4 led us to investigate the role of chlorine in the growth of silicon nanowires[5]. The main HCl effect was reported to be the chlorination of the silicon surface, which reduces the gold migration and enables the growth of small diameter silicon nanowire down to 20nm at 650°C. We report in the first part of this work that the effect of HCl is gradual and that the minimum diameter of the growing wires depends on the HCl partial pressure. We then investigate the role of HCl in the early growth of SiNWs to determine the optimum growth conditions. EXPERIMENTS The SiNWs were grown in a Low Pressure Chemical Vapour Deposition (LP-CVD) reactor from Epigress at total pressure of 20 mbar. Hydrogen (H2) was used as a carrier gas at 3.5 standard litres per minute. Typical partial pressures used for SiH4 or HCl range from 0 to 0.5 mbar. Samples were images after growth by Scanning Electron Microscopy (SEM) at 10 keV. The Table 1 reports the minimum diameter of the growing nanowires depending on the HCl partial pressure.
Temperature (°C) SiH4 partial pressure (mbar) HCl partial pressure (mbar) Minimum diameter
650°C
650°C
650°C
650°C
0.13
0.13
0.13
0.13
0
0.05
0.13
0.52
70
60
30
20
Table 1 : Minimum observed diameter of SiNWs obtained from a 2nm gold dewetted thin film on Si[111] substrate. The deposit sequence is the same for all samples, starting wi
Data Loading...
