Photoluminescence Activity of Neodymium-Doped Gallium Oxide Thin Films
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1111-D07-04
Photoluminescence Activity of Neodymium-doped Gallium Oxide Thin films C. Lecerf, P. Marie, C. Frilay, J. Cardin and X. Portier CIMAP-CEA-CNRS UMR 6252-ENSICAEN-Université de Caen, 6 Boulevard Maréchal Juin, 14050 Caen Cedex 4, France ABSTRACT Photoluminescence activity was observed for neodymium-doped gallium oxide thin films prepared by radiofrequency magnetron co-sputtering. Structural and optical properties of asgrown and annealed films were studied and photoluminescence activity was especially investigated. The most intense lines were associated to the 4F3/2 4I9/2 and 4F3/2 4I11/2 electronic transitions of Nd3+. The effects of deposition and treatment parameters such as the substrate temperature, the post anneal treatment or the neodymium content in the films were particularly examined with the aim to reach the best luminescence efficiency. INTRODUCTION Studies of Transparent Conducting Oxide (TCO) semiconductors attract much attention because of their numerous applications in electronic devices, such as flat panel displays, solar cells, waveguides or high-temperature stable gas sensors [1,2,3,4]. Most of these devices require optoelectronic tools which need transparent electrodes, i.e. a thin film of a TCO semiconductor. So far, Indium Tin Oxide (ITO) thin films were mainly used. However, recent developments in optoelectronic devices need transparent thin films electrodes with specific properties, such as lower resistivity and higher optical transmittance [5]. Furthermore, due to the high cost and the limited supply of indium and with the market expansion of optoelectronic devices which need ITO, it appears also an urgent need of alternatives TCOs. The monoclinic phase of gallium oxide (β-Ga2O3) belongs to these promising TCOs. Its wide band gap of about 4.8-5 eV provides the possibility of light emission in the infrared, visible and ultraviolet spectral regions [6,7]. In addition, it presents very high chemically and thermally stabilities (melting point at 1800°C) and can be easily obtained by basic annealing treatments [3]. Optical and luminescent properties of rare-earth doped β-Ga2O3 make this semiconductor particularly interesting [4]. Monoclinic β-Ga2O3 phase can be described by its space group C2/m and cell parameters a=1.221 nm ; b=0.304 nm ; c=0.580 nm and β=103.8° [8]. β-Ga2O3 thin films have been fabricated with different techniques such as electron beam evaporation [9], spray pyrolysis deposition [10], sol gel process [11], and radiofrequency (RF) magnetron sputtering [8,12]. While in a previous work [8] undoped β-Ga2O3 polycrystalline thin films were mostly studied, the present article is concentrated on neodymium-doped gallium oxide (Ga2O3: Nd3+). Similarly, Ga2O3: Nd3+ thin films have been prepared by RF magnetron co-sputtering. Studies are especially focused on their luminescence properties. Substrate temperature, annealing temperature as well as neodymium content in the film are considered to reveal their influence on the structure and the luminescence.
EXPERIMENT Ga2O3: Nd3
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