Abstract ZnSe nanostructures were grown on Si substrates by Au catalyzed vapor phase growth at 725°C. Three different types of ZnSe nanosaws have been observed using transmission electron microscopy (TEM). Detailed structural and microstructural inves- tigation has been carried out using electron diffraction and high-resolution TEM (HRTEM). It has been found that stacking faults and phase transformation are important features of the nanosaw formation. The controlled formation of these ZnSe nanosaws could have very important device applications. ZnSe is a wide-band-gap II–VI semiconductor, which is suitable for blue and green light emission. ZnSe-based microstructures have been widely investigated in re- cent years for their potential optoelectronic applica- tions [1, 2]. Controlling the formation of different ZnSe nanostructures, as well as achieving well-confined interfaces induced by structural modulations, may further lead to novel properties and promising appli- cations in nanoscale optoelectronic devices [3–6]. For the II–VI semiconductor nanostructures such as CdSe, ZnO and ZnS, wurtzite-structured nanobelts and nanosaws have been fabricated by thermal evap- oration, and their growth mechanisms have been studied in detail [7–11]. Recently, both zinc-blende- and wurtzite-structured ZnSe nanowires and nanorib- bons [11–15], depending on growth methods, have also been reported. However, no detailed investigations of ZnSe nanosaws have been reported. In this Letter, we report on the observation of three different types of ZnSe nanosaws produced by Au catalyzed vapor–liquid–solid (VLS) growth. A detailed structural and microstructural investigation of these nanosaws is presented and a formation mechanism is proposed. ZnSe nanostructures were grown on n-type (111) Si wafers by standard vapour phase growth method at 725°C. The Si substrate was first cleaned and a thin layer of Au (50 nm) was deposited by thermal evaporation. The source material was pure ZnSe powder (99.999% purity). The Si substrates were placed at the down- stream end of flowing Ar gas and the source tempera- ture was rapidly raised to 1000°C, while the substrate was at 725°C. The nanostructures were found to grow preferentially on the Au catalyst locations. The samples for transmission electron microscopy (TEM) examina- tions were prepared by scraping the products off the substrate, and dispersing them onto a copper grid coated with a lacey carbon film. Selected-area electron diffraction (SAED), bright-field (BF) imaging, high- angle annular dark-field (HAADF) imaging, high res- olution transmission electron microscopy (HRTEM), and energy dispersive x-ray spectroscopy (EDS) anal- yses were performed using a field-emission gun, scan- ning transmission electron microscopy (STEM) operating at 200 kV equipped with an imaging filter. The products were extensively examined using STEM. Three different types of ZnSe nanostructures were observed: nanowires, nanoribbons and nanosaws, Y. Q. Wang Æ K. L. Kavanagh (&) Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada e-mail: kavanagh@sfu.ca U. Philipose Æ H. Ruda Center for Advanced Nanotechnology, University of Toronto, Toronto, Ontario M5S 3E4, Canada J Mater Sci: Mater Electron (2006) 17:1065–1070 DOI 10.1007/s10854-006-9006-6 123 Planar defects and phase transformation in ZnSe nanosaws Y. Q. Wang Æ U. Philipose Æ H. Ruda Æ K. L. Kavanagh Received: 16 June 2006 / Accepted: 29 June 2006 / Published online: 31 August 2006 Ó Springer Science+Business Media, LLC 2006