Formation of the Thermoelectric Candidate Chromium Silicide by Use of a Pack-Cementation Process

• Published in: Journal of electronic materials 2014-10, Vol.43 (10), p.3733-3739
• Main Authors: Stathokostopoulos, D., Chaliampalias, D., Tarani, E., Theodorakakos, A., Giannoulatou, V., Polymeris, G.S., Pavlidou, E., Chrissafis, K., Hatzikraniotis, E., Paraskevopoulos, K.M., Vourlias, G.
• Format: Article
• Language: English
• Subjects: Cement; Characterization and Evaluation of Materials; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conductivity phenomena in semiconductors and insulators; Cross-disciplinary physics: materials science; rheology; Electric power; Electronic transport in condensed matter; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials Science; Methods of deposition of films and coatings; film growth and epitaxy; Optical and Electronic Materials; Physics; Silicon; Solid State Physics; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Thermodynamics; Thermoelectric and thermomagnetic effects
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-014-3100-y

Transition-metal silicides are reported to be good candidates for thermoelectric applications because of their thermal and structural stability, high electrical conductivity, and generation of thermoelectric power at elevated temperatures. Chromium disilicide (CrSi 2 ) is a narrow-gap semiconductor and a potential p -type thermoelectric material up to 973 K with a band gap of 0.30 eV. In this work, CrSi 2 was formed from Si wafers by use of a two-step, pack-cementation, chemical diffusion method. Several deposition conditions were used to investigate the effect of temperature and donor concentration on the structure of the final products. Scanning electron microscopy and x-ray diffraction analysis were performed for phase identification, and thermal stability was evaluated by means of thermogravimetric measurements. The results showed that after the first step, chromizing, the structure of the products was a mixture of several Cr–Si phases, depending on the donor (Cr) concentration during the deposition process. After the second step, siliconizing, the pure CrSi 2 phase was formed as a result of Si enrichment of the initial Cr–Si phases. It was also revealed that this compound has thermoelectric properties similar to those reported elsewhere. Moreover, it was found to have exceptional chemical stability even at temperatures up to 1273 K.