High-frequency electron paramagnetic resonance study of the as deposited and annealed carbon-rich hydrogenated amorphous
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1069-D07-11
High-frequency electron paramagnetic resonance study of the as deposited and annealed carbon-rich hydrogenated amorphous silicon-carbon films A. V. Vasin1, E. N. Kalabukhova1, S. N. Lukin1, D. V. Savchenko1, V. S. Lysenko1, A. N. Nazarov1, A. V. Rusavsky1, and Y. Koshka2 1 V. E. Lashkaryov Institute of Semiconductor Physics, NASU, Pr. Nauki 45, Kiev, 03028, Ukraine 2 Mississippi State University, 216 Simrall Hall, Box 9571, Mississippi State, MS, 39762 ABSTRACT Three paramagnetic defects were revealed in amorphous hydrogenated carbon-rich silicon-carbon alloy films (a-SiC:H), which were attributed to the to silicon (Si) dangling bonds (Si DB), carbon-related defects (CRD), and bulk Si DB defect bonded with nitrogen atoms SiN2Si. The effect of thermal annealing on a-SiC:H films was studied. It was established that annealing at high temperatures leads to formation of graphite-like carbon clusters in a-SiC:H films and strong increase of the concentration of CRD, while EPR signal from Si DB disappeared. A dependence of the resonance positions for both Si DB and CRD signals on the orientation of the magnetic field relative to the a-SiC:H film plane was found at Q-band and Dband frequencies and was explained by the influence of demagnetizing fields, which is becoming significant at high spin density of the paramagnetic centers, higher microwave frequency, and low temperature. A demagnetizing field of 11 Gs was found in annealed a-SiC:H film at 140 GHz and 4.2 K. INTRODUCTION The hydrogenated amorphous carbon-rich silicon-carbon alloy films (a-Si0.3C0.7:H) has attracted great interest since they can be used for production of a large variety of materials with tuneable electrical, optical, and light emitting properties. However, the influence of preparation conditions and metastable paramagnetic defects on stability of electronic properties of a-SiC:H films are not yet well understood. The previous EPR study of the paramagnetic defects in nearstochiometric and carbon-rich a-SiC:H films was performed at X-band frequency (9.4 GHz). and EPR spectrum was represented by an isotropic single line with g = 2.0028. [1,2]. The investigation was mainly concentrated on the analysis of total concentration of paramagnetic defects and the width of the isotropic single line. We present in this paper the results of high frequency (37 GHz and 140 GHz) EPR study of the carbon-rich a-SiC:H films and effects of thermal annealing. Our results show that in fact not one but three EPR lines contribute to the isotropic line observed at X-band frequency. A dependence of the resonance positions of EPR signals on the orientation of the magnetic field relative to the film plane was observed and attributed to the influence of demagnetizing fields.
EXPERIMENTAL DETAILS Amorphous hydrogenated silicon-carbon alloy film (a-SiC:H) was deposited by reactive dc-magnetron sputtering of a monocrystalline silicon target using a mixture of Ar/CH4 as working gas. Two-side polished Si (100) wafers (p-type, 40 Ohm·cm) were used as substrates. The substra
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