Title: Nanometer-Thick Gold on Silicon as a Proxy for Single-Crystal Gold for the Electrodeposition of Epitaxial Cuprous Oxide Thin Films

Abstract

Here, single-crystal Au is an excellent substrate for electrochemical epitaxial growth due to its chemical inertness, but the high cost of bulk Au single crystals prohibits their use in practical applications. Here, we show that ultrathin epitaxial films of Au electrodeposited onto Si(111), Si(100), and Si(110) wafers can serve as an inexpensive proxy for bulk single-crystal Au for the deposition of epitaxial films of cuprous oxide (Cu₂O). The Au films range in thickness from 7.7 nm for a film deposited for 5 min to 28.3 nm for a film deposited for 30 min. The film thicknesses are measured by low-angle X-ray reflectivity and X-ray Laue oscillations. High-resolution TEM shows that there is not an interfacial SiO_x layer between the Si and Au. The Au films deposited on the Si(111) substrates are smoother and have lower mosaic spread than those deposited onto Si(100) and Si(110). The mosaic spread of the Au(111) layer on Si(111) is only 0.15° for a 28.3 nm thick film. Au films deposited onto degenerate Si(111) exhibit ohmic behavior, whereas Au films deposited onto n-type Si(111) with a resistivity of 1.15 Ω·cm are rectifying with a barrier height of 0.85 eV. The Au and the Cu₂O follow themore » out-of-plane and in-plane orientations of the Si substrates, as determined by X-ray pole figures. The Au and Cu₂O films deposited on Si(100) and Si(110) are both twinned. The films grown on Si(100) have twins with a [221] orientation, and the films grown on Si(110) have twins with a [411] orientation. An interface model is proposed for all Si orientations, in which the –24.9% mismatch for the Au/Si system is reduced to only +0.13% by a coincident site lattice in which 4 unit meshes of Au coincide with 3 unit meshes of Si. Although this study only considers the deposition of epitaxial Cu₂O films on electrodeposited Au/Si, the thin Au films should serve as high-quality substrates for the deposition of a wide variety of epitaxial materials.« less

Authors:

Switzer, Jay A. ^[1]; Hill, James C. ^[1]; Mahenderkar, Naveen K. ^[2]; Liu, Ying-Chau ^[1]

---

+ Show Author Affiliations

1. Department of Chemistry and Graduate Center for Materials Research, Missouri University of Science and Technology, Rolla, Missouri 65409-1170, United States, and
2. Department of Materials Science and Engineering and Graduate Center for Materials Research, Missouri University of Science and Technology, Rolla, Missouri 65409-1170, United States

Publication Date:

Tue Jun 07 00:00:00 EDT 2016

Research Org.:

Missouri Univ. of Science and Technology, Rolla, MO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1256140

Alternate Identifier(s):

OSTI ID: 1258615

Grant/Contract Number:  

FG02-08ER46518

Resource Type:

Published Article

Journal Name:

ACS Applied Materials and Interfaces

Additional Journal Information:

Journal Name: ACS Applied Materials and Interfaces Journal Volume: 8 Journal Issue: 24; Journal ID: ISSN 1944-8244

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; electrodeposition; epitaxy; thin films; gold; cuprous oxide; silicon; coincident site lattice