Same Precursor, Two Different Products: Comparing the Structural Evolution of In-Ga-O "Gel-Derived" Powders and Solution-Cast Films Using Pair Distribution Function Analysis.
Amorphous metal oxides are central to a variety of technological applications. In particular, indium gallium oxide has garnered attention as a thin-film transistor channel layer material. In this work we examine the structural evolution of indium gallium oxide gel-derived powders and thin films using infrared vibrational spectroscopy, X-ray diffraction, and pair distribution function (PDF) analysis of X-ray total scattering from standard and normal incidence thin-film geometries (tfPDF). We find that the gel-derived powders and films from the same aqueous precursor evolve differently with temperature, forming mixtures of Ga-substituted In2O3and In-substituted β-Ga2O3with different degrees of substitution. X-ray total scattering and PDF analysis indicate that the majority phase for both the powders and films is an amorphous/nanocrystalline β-Ga2O3phase, with a minor constituent of In2O3with significantly larger coherence lengths. This amorphous β-Ga2O3phase could not be identified using the conventional Bragg diffraction techniques traditionally used to study crystalline metal oxide thin films. The combination of Bragg diffraction and tfPDF provides a much more complete description of film composition and structure, which can be used to detail the effect of processing conditions and structure-property relationships. This study also demonstrates how structural features of amorphous materials, traditionally difficult to characterize by standard diffraction, can be elucidated using tfPDF.
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
Suzannah R
0000-0002-7208-7681
SR
Wood
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
Keenan N
KN
Woods
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
Paul N
PN
Plassmeyer
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
David A
DA
Marsh
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
Darren W
0000-0001-5967-5115
DW
Johnson
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
Catherine J
0000-0002-4545-7835
CJ
Page
Department of Chemistry, University of Copenhagen , 2100 Copenhagen, Denmark.
Kirsten M Ø
KMØ
Jensen
Department of Chemistry and Biochemistry, and Material Science Institute, University of Oregon , Eugene, Oregon 97403, United States.
David C
0000-0002-1118-0997
DC
Johnson