Domain matching epitaxy of cubic In2O3 on r‐plane sapphire. Issue 7 (17th March 2015)

• Record Type: Journal Article
• Authors: Vogt, Patrick; Trampert, Achim; Ramsteiner, Manfred; Bierwagen, Oliver
• Is Part Of: Physica status solidi. Volume 212:Issue 7(2015:Jul.)
• Page Start: 1433
• Page End: 1439
• Publication Date: 2015-03-17
• Subjects: Solid state physics -- Periodicals; Solids -- Industrial applications -- Periodicals; 530.41
• DOI: 10.1002/pssa.201431889
• Languages: English
• ISSNs: 1862-6300

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="pssa201431889-sec-0001" sec-type="section"> <p>Undoped, Sn‐doped, and Mg‐doped In<sub>2</sub>O<sub>3</sub> layers were grown on rhombohedral <italic>r</italic>‐plane sapphire (α‐Al<sub>2</sub>O<sub>3</sub> (10.2)) by plasma‐assisted molecular beam epitaxy. X‐ray diffraction and Raman scattering experiments demonstrated the formation of phase‐pure, cubic (110)‐oriented In<sub>2</sub>O<sub>3</sub> for Sn‐ and Mg‐concentrations up to 2 × 10<sup>20</sup> and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj1m9pmqvt" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14381656:media:pssa201431889:pssa201431889-math-0009" display="inline" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>6</mml:mn><mml:mo /><mml:mo>×</mml:mo><mml:mo /><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>20</mml:mn></mml:mrow></mml:msup><mml:mo /><mml:msup><mml:mtext>cm</mml:mtext><mml:mrow><mml:mo>−</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math></alternatives></inline-formula>, respectively. Scanning electron microscopy images showed facetted domains without any surface‐parallel (110) facets. High Mg‐ or Sn‐doping influenced surface morphology and the facet formation. X‐ray diffraction <italic>Φ</italic>‐scans indicated the formation of two rotational domains separated by an angle <italic>Ф</italic> = 86.6° due to the substrate mirror‐symmetry around the in‐plane‐projected Al<sub>2</sub>O<sub>3</sub><italic>c</italic>‐axis. The in‐plane epitaxial relationships to the substrate were determined for both domains. For the first domain it is <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj1m9pmqdn" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14381656:media:pssa201431889:pssa201431889-math-0010" display="inline" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mtext>Al</mml:mtext><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>O</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mrow><mml:mo stretchy="true">[</mml:mo><mml:mn>01.0</mml:mn><mml:mo stretchy="true">]</mml:mo><mml:mtext> </mml:mtext><mml:mo>∥</mml:mo><mml:mtext> </mml:mtext></mml:mrow><mml:msub><mml:mtext>In</mml:mtext><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>O</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mo /><mml:mrow><mml:mo stretchy="true">[</mml:mo><mml:mn>3</mml:mn><mml:mover accent="true"><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mo>¯</mml:mo></mml:mover><mml:mtext> </mml:mtext><mml:mover accent="true"><mml:mrow><mml:mn>4</mml:mn></mml:mrow><mml:mo>¯</mml:mo></mml:mover><mml:mo stretchy="true">]</mml:mo></mml:mrow></mml:mrow></mml:math></alternatives></inline-formula>. For the second domain the inplane epitaxial relation is <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgj1m9pmpb1" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14381656:media:pssa201431889:pssa201431889-math-0011" display="inline" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mtext>Al</mml:mtext><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>O</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mrow><mml:mo stretchy="true">[</mml:mo><mml:mn>01.0</mml:mn><mml:mo stretchy="true">]</mml:mo><mml:mtext> </mml:mtext><mml:mo>∥</mml:mo><mml:mtext> </mml:mtext></mml:mrow><mml:msub><mml:mtext>In</mml:mtext><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>O</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mo /><mml:mrow><mml:mo stretchy="true">[</mml:mo><mml:mn>3</mml:mn><mml:mover accent="true"><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mo>¯</mml:mo></mml:mover><mml:mn>4</mml:mn><mml:mo stretchy="true">]</mml:mo></mml:mrow></mml:mrow></mml:math></alternatives></inline-formula>. A low‐mismatch coincidence lattice of indium atoms from the film and oxygen atoms from the substrate rationalizes this epitaxial relation by domain‐matched epitaxy. Cross‐sectional transmission‐electron microsopy showed a columnar domain‐structure, indicating the vertical growth of the rotational domains after their nucleation.</p> <p>Coincidence structure of In<sub>2</sub>O<sub>3</sub> (110) (In atoms in red) grown on Al<sub>2</sub>O<sub>3</sub> (10.2) (O atoms in blue) showing two rotational domians.<inline-graphic xlink:href="ark:/27927/pgj1m9pmb53" content-type="pssa201431889-gra-0001" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></p> </sec> </abstract>