JOHN G. EKERDT RESEARCH FOCUS

Transcription

1 JOHN G. EKERDT RESEARCH FOCUS We study the surface, growth and materials chemistry of ultrathin metal and dielectric films. Our work seeks to: 1) develop and understand the reactions and chemistry that control nucleation and growth of films, and 2) understand the properties of these materials and relate the properties to structure, bonding and growth. The programs are motivated by applications in electronic materials, energy and sensors.

2 JOHN G. EKERDT Projects Subject Areas Fundamental Aspects Technology Applications Nucleation and Growth of Ultrathin Metal Films Selective Growth of Metal and Dielectric Films Epitaxial Growth and Properties of Crystalline Oxides and Perovskites Limits of Nanoshape Control Surface Science Materials Science Nanotechnology Materials Chemistry Reaction Kinetics Atomic Layer Deposition Chemical Vapor Deposition Molecular Beam Epitaxy Reactive and Atomic Layer Etching Chemical nature of surface sites that serve as activation sites and nucleation sites Enabling chemistry for film growth or nanoparticle growth Nature of bonding across interfaces Approaches to stabilizing metastable structures Relations between bonding, structure and properties Selective activation of surfaces with ions and radicals Advanced memory devices Sensors Diffusion barriers for advanced microelectronic devices Low power devices Integration of functional crystalline oxides on Si(001), Ge(001) and GaN(0001)

3 Low Temperature ALD of Crystalline Oxides Shen Hu; Ed Lin; Bryce Edmondson; Pei-Yu Chen SrTiO 3 template Si substrate McDaniel, et al., Appl. Phys. Rev. 2, (2015). Atomic Layer Deposition Commercial metalorganic precursors Oxidant = water T = C, P 1 torr 1.6-nm SrTiO 3 buffer by MBE needed on Si(001) ADF 1 nm Ge SHTO EELS Mapping ALD directly on Ge(001) SrTiO 3, SrHfO 3, Sr(Hf,Ti)O 3, SrZrO 3, BaTiO 3 McDaniel,et al. Adv. Mater. Interf. 1, (2014). A scaleable, low cost of ownership approach with potential for 3D structures. Enables coupling of function directly to the substrate. Sr Ti Hf S. Hu with H-W. Wu and D. Smith of ASU.

4 The Materials Physics Laboratory A shared facility located in RLM and managed by a Senior Scientist, Agham Posadas Allows for co-location of students from the A. A. Demkov and J. G. Ekerdt groups working on common projects We study the monolithic integration of crystalline oxides on substrates of the future, such as Ge(001), and GaN(0001) and AlGaN(0001). We seek the properties promised by crystalline layers.

5 How to Grow Crystalline Rare Earth Oxides on Nitrides? Employ Crystalline Zintl Layer La 2 O 3, Gd 2 O 3 and Er 2 O 3 Ionic oxides on a highly covalent semiconductor Lattices align surface energy (wetting) needs to be resolved Zintl compounds A a X x (A = Group 1, 2; X = Group 3, 4, 5), such as SrGa 2, SrAl 2, and EuGa 2 support/bridge ionic and covalent bonding structures. Enables coupling of function directly to the substrate.

6 Selective Growth of Metal and Dielectric Films Now do this over topography TiN ALD Sonali Chopra Zizhuo Zhang Himmi Nallan Brennan Coffee H. Lee, S. F. Bent (2012). SAM density at regions of high curvature enable this Untreated surface Treated with n-decyldimethylchlorosilane prior to TiN ALD TiN We seek selective chemical routes to form the metallic lines over topography, magnetic lines and structures, and selective chemical routes to etch metals. No CoO ALD CoO reduced to Co ALD on ODStreated HfO nm TiN visible everywhere 100 nm Treated with n-decyldimethylchlorosilane prior to TiN ALD TiN No TiN visible Counts [arb. units] Co 2p SrO/Co/SiO Binding Energy [ev] 100 nm

7 Selective ALD for Nanofabrication: Retaining Atomic Precision Zyvex Labs writes features, protects with TiO 2, etches surrounding Si. (b) Deposit SAM F-based Etch Transfer SnO x Reduction Alkyne CEG Selective SnO x ALD This program will elucidate the role of reactive sites and molecular structure in retaining the atomic precision written in the H-terminated Si.