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Thermal annealing effects on the optical and electrical properties of a-SiC:H thin films sputtered at different hydrogen flow rates

L. MAGAFAS1,* , C. MERTZANIDIS2, D. BANDEKAS1, N. ATHANASIADES3

Affiliation

  1. Department of Electrical Engineering, Technological Educational Institute of Kavala, St. Loukas 65404 Kavala, Greece
  2. Department of Industrial Informatics, Technological Educational Institute of Kavala, St. Loukas, 65404 Kavala, Greece
  3. Senior Engineer, Hellenic Transmission System Operator (HTSO), Operational Planning Department, Asklipiou Street 22, 14568, Krioneri, Athens, Greece

Abstract

In this paper we study the effect of annealing process on the optical and electrical properties of the a-SiC:H thin films sputtered at three different hydrogen flow rates 9 sccm, 14 sccm and 20 sccm. Optical transmission measurements have shown that the optical band gap, Eg, is affected by thermal annealing when Ta>575 oC, due to emission of hydrogen bonded to silicon. For hydrogen flow rate 9 sccm, the evaluation of the optical and electrical measurements have shown that for 400 oC<Ta≤ 550 oC the quality of the a-SiC:H thin films presents a reasonable improvement, with the optimum result been achieved at Ta = 550 oC remaining there up to 575 oC. This behavior is attributed to the relaxation of the strain in the amorphous network. Further increase of Ta causes emission of hydrogen bonded to silicon, leading to rapid deterioration of the properties of the amorphous semiconductor. As the hydrogen flow rate increases from 9 sccm to 20sccm, the optimum material quality is achieved at higher Ta, since the emission of a small quantity of hydrogen enables additional relaxation in the amorphous network. Finally, the maximum values of photosensitivity of the annealed a-SiC:H thin films (≅1500) in combination with the corresponding values of Eg make these films very interesting for applications as optical sensor devices and solar cells..

Keywords

Amorphous semiconductor, Thermal annealing, Optical properties, Electrical properties.

Submitted at: Feb. 8, 2007
Accepted at: July 15, 2007

Citation

L. MAGAFAS, C. MERTZANIDIS, D. BANDEKAS, N. ATHANASIADES, Thermal annealing effects on the optical and electrical properties of a-SiC:H thin films sputtered at different hydrogen flow rates, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 7, pp. 2030-2035 (2007)