Optimization of large power factor in molybdenum oxide thin films deposited on Si substrate

The performance of thermoelectric (TE) thin films strongly depends on the substrates. In our previous study, we investigated the power factor (PF) 1.78 mW/(m . K-2) at 700 K in MoO2+x thin film grown on single crystalline Si, comparable to the state of art in other TE thin films. Such boosted PF originates mainly from the significantly enhanced Seebeck coefficient, correlated with the contribution of the Si substrate. In this paper, the PF has been prominently optimized up to 12.5 mW/(m . K-2) at 668 K by adjusting the thickness of MoO2+x film in the MoO2+x/Si system, which could be understood in the frame work of parallel slab model. Experimentally, the effective TE properties were susceptible to the substrate-film interface. The existence of Mo in MoO2+x film might limit the formation of SiO2 interfacial layer. These results suggest a simple, low-cost, scalable technique route to explore highly effective TE devices.