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Title: Atomic layer deposition of crystalline SrHfO{sub 3} directly on Ge (001) for high-k dielectric applications

The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO{sub 3} (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10{sup −5} A/cm{sup 2} at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (D{sub it}) is estimated to be as low as ∼2 × 10{sup 12 }cm{sup −2 }eV{sup −1} under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased D{sub it} value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.
Authors:
; ;  [1] ; ; ;  [2] ; ;  [3] ; ;  [4]
  1. Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)
  2. Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)
  3. Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)
  4. Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
22413046
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; CRYSTAL STRUCTURE; DEPOSITION; DIELECTRIC MATERIALS; EPITAXY; FILMS; GERMANIUM; HAFNATES; INTERFACES; LEAKAGE CURRENT; PERMITTIVITY; STRONTIUM COMPOUNDS; TRANSISTORS; TRANSMISSION ELECTRON MICROSCOPY; TRAPS; X-RAY DIFFRACTION