Concentration Quenching of Tb 3+ Doped SiC:H and AlN Thin Films in Photoluminescence and Cathodoluminescence Measurement
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Concentration Quenching of Tb3+ Doped SiC:H and AlN Thin Films in Photoluminescence and Cathodoluminescence Measurements J. A. Guerra1,2, F. Benz3, L. Montañez1, R. Grieseler4, P. Schaaf4, F. De Zela1, A. Winnacker2, H. P. Strunk3, R. Weingärtner1,2 1
Pontifical Catholic University of Peru, Sciences Department, Physics Section, Av. Universitaria 1801, Lima 32, Peru. 2 University of Erlangen-Nurnberg, Institute of Material Science 6, Martensstr. 7, 91058 Erlangen, Germany 3 University of Stuttgart, Institute of Materials Science, Chair of Material Physics, Heisenbergstr. 3, 70569 Stuttgart, Germany 4 Technical University of Ilmenau, Institute of Materials Technology, POB 100565, 98684 Ilmenau, Germany.
ABSTRACT We present a systematic study of photo- and cathodoluminescence measurements in the visible of Terbium doped SiC:H and AlN thin films. The Terbium atomic concentrations vary from 0.9 to 10% for the SiC:H and from 0.8 to 6% for the AlN samples. For both materials the increase of the emission intensity with concentration and the subsequent quenching effect can be seen. The optimal concentration for the highest light emission is found. Photoluminescence excitation spectroscopy addresses the enhancement light emission mechanisms of the principal emission electronic transition of Terbium at ~542 nm. INTRODUCTION Rare earth (RE) doped wide bandgap semiconductors have gathered attention in the past decade for various optoelectronic applications [1-6]. Their main asset is that their emission spectra hardly depend on the host matrix due to the fact that the electronic transitions involved occur between energy levels that are shielded from the bonding electrons. Furthermore, wide bandgap materials are transparent in the visible region and the RE light emission intensity can be enhanced through thermal annealing treatments and/or bandgap engineering of the host matrix [7-12]. Little is known concerning the different excitation mechanisms. The main drawback of the RE emission application in optoelectronic devices is the concentration quenching effect, which limits the amount of dopant introduced in the host matrix, and therefore limits the maximum achievable intensity. While the light emission concentration quenching effect is well accepted, there are only few characterizations of this process under different excitation sources [6,12]. Recently, S. Chen et al (APL 96 2010) proposed a suppression of the concentration quenching effect in Er doped GaN through CL upon high excitation power density [6]. Moreover, H. J. Lozykowski et al (APL 76 2000), showed the full emission of Tb doped
GaN by means of CL characterization upon a high beam current (~75 µA). Such spectra exhibited that the emission intensity related to the 5D3 level is comparable to those related to the 5D4 [8,9]. In this paper, we report the observation of both the cathodoluminescence (CL) and the photoluminescence (PL) spectra of Terbium doped SiC:H and AlN thin films and its behavior for different Terbium concentrations. EXPERIMENTAL DETAILS Sample prepar
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