On the Growth of SrMoO ₃ Films for UV-C LEDs Applications: Deposition Issues and Solutions

SrMoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> (SMO) thin films offer exceptional UV transparency and metallic conductivity, making them ideal transparent electrodes for UV-C LEDs. However, their deposition is challenged by thermodynamic instability, where trace oxygen triggers oxidation to insulating <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SrMoO}_{4}$</tex>. This study employs pulsed laser deposition (PLD) under either high vacuum or oxygen, or argon atmosphere, to grow epitaxial SMO on latticematched (001) LSAT and (110) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{GdScO}_{3}$</tex> substrates. Structural and electrical characterization reveals that oxygen pressures induce <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SrMoO}_{4}$</tex> formation, increasing sheet resistance. Critically, postdeposition vacuum annealing at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8^{\circ} \mathbf{8 5}^{\circ} \mathrm{C}$</tex> decomposes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SrMoO}_{4}$</tex> inclusions, reducing resistance by three orders of magnitude. These results establish oxygen suppression during growth and corrective annealing as essential strategies for realizing highconductivity SMO electrodes in UV-C optoelectronics.