Optimizing Thermoelectric Power Factor in p-Type Hydrogenated Nano-crystalline Silicon Thin Films by Varying Carrier Concentration

• Published in: Journal of electronic materials 2019-04, Vol.48 (4), p.2085-2094
• Main Authors: Acosta, E., Smirnov, V., Szabo, P. S. B., Buckman, J., Bennett, N. S.
• Format: Article
• Language: English
• Subjects: Carrier density; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal structure; Crystallinity; Electrical resistivity; Electronics and Microelectronics; Heat conductivity; Heat transfer; Hydrogenation; Instrumentation; Materials Science; Optical and Electronic Materials; Organic chemistry; Plasma enhanced chemical vapor deposition; Power factor; Seebeck effect; Silicon films; Solid State Physics; Substrates; Thermal conductivity; Thermoelectricity; Thin films
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-019-07036-6

Most approaches to silicon-based thermoelectrics are focused on reducing the lattice thermal conductivity with minimal deterioration of the thermoelectric power factor. This study investigates the potential of p -type hydrogenated nano-crystalline silicon thin films ( μ c-Si:H), produced by plasma-enhanced chemical vapor deposition, for thermoelectric applications. We adopt this heterogeneous material structure, known to have a very low thermal conductivity (~ 1 W/m K), in order to obtain an optimized power factor through controlled variation of carrier concentration drawing on stepwise annealing. This approach achieves a best thermoelectric power factor of ~ 3 × 10 −4  W/mK 2 at a carrier concentration of ~ 4.5 × 10 19  cm 3 derived from a significant increase of electrical conductivity ~ × 8, alongside a less pronounced reduction of the Seebeck coefficient, while retaining a low thermal conductivity. These thin films have a good thermal and mechanical stability up to 500°C with appropriate adhesion at the film/substrate interface.