Control of heterointerface and strain mapping in Au catalyzed axial Si-Si 1-x Ge x nanowires
- PDF / 6,320,282 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 116 Downloads / 197 Views
Control of heterointerface and strain mapping in Au catalyzed axial Si-Si1-xGex nanowires P. Periwal1, G. Patriarche2, L. Latu-Romain1, B. Salem1, F. Bassani1, T. Baron1 1
Laboratoire des Technologies de la Microélectronique (LTM), UMR 5129 CNRS-UJF, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble, France 2
Laboratoire de Photonique et de Nanostructures (LPN)-CNRS, Route de Nozay, 91460 Marcoussis, France ABSTRACT Axial heterostructure nanowires with Si and SiGe segments have been grown using Au metal seed as catalyst by chemical vapor deposition (CVD) via vapor-liquid-solid process (VLS). We report on the effect of growth intervention on the droplet stability which in turn modifies NW morphology and interfacial abruptness. Growth stop of 2 minutes on transition from one material to another have been demonstrated to suppress reservoir effect by Au catalyst. The two SiGe/Si and Si/SiGe heterointerfaces are found to be assymetric. The former being diffused while the latter one is sharp. Furthermore, geometric phase analysis reports elastic deformation at the heterointerface. Nanowire undergoes rotation in both clock and anticlockwise direction at their sidewalls with an angle of 2.5° in order to accommodate this strain. INTRODUCTION
During the last decade, semiconductor nanowires (NWs) have been an extensive subject of research due to their properties and great potential in various applications1-4. To add more functionalities in NW based devices, heterostructures are promising candidate. The success of heterostructure NW based device is largely dependent on controlled doping5 and quality of heterointerfaces in them6. Bottom up synthesis of NWs7 using Au catalyst seed for NW growth suffers from a severe problem of reservoir effect8. Recently, due to this effect, abrupt junctions in catalyzed heterostructured nanowires have emerged as an interesting subject of research. Li et al9 have described interfacial broadening by theoretical/modeling and simulations, where it is linearly dependent on NW diameter. This observation was verified by Clark and coworkers10. Recent research has focused on changing the catalyst with reduced solubility of Si and Ge in it such that no composition graded region is seen. Compositionally abrupt interfaces have been generated by Au-Al11, or Au-Ga12, Au-Ag13 alloy but use of Al or Ga produces risk of doping. Al or Ga acts as a p-type dopant source for Si or Ge. So, NW diameter or chemical nature of the catalyst enables to control interfacial broadening. But, to our knowledge, no studies show the influence of growth parameters on the interfacial abruptness in Si-Si1-xGex hNWs although such interruptions are very popular in axial NWs using III-V materials14. Moreover, the difference in lattice parameter of Si and Ge causes strains at the heterointerface. Here, we demonstrate the impact of growth interventions on the abruptness and morphology of heterointerfaces and report an optimized growth
parameter which minimizes reservoir effect exhibited by Au catalyst. We report strain study on Si/Si
Data Loading...
