Enhanced Cross-plane Thermoelectric Transport of Rotationally-disordered SnSe₂ via Se Vapor Annealing

In this talk I will review our recent progress in cross-plane thermoelectric measurements of SnSe and SnSe₂ films grown by the modulated element reactant (MER) approach. The initially grown SnSe films have relatively low cross-plane Seebeck coefficients due to significant unintentional doping originating from Se vacancies. By performing post-growth annealing at a fixed Se partial pressure, a transition from SnSe to SnSe₂ is induced. This results in a 16-fold increase in the cross-plane Seebeck coefficient (from -38.6 to -631μV/K) after Se annealing due to both the SnSe to SnSe₂ transition and the mitigation of unintentional doping by Se vacancies. The power factor S²σ increased by 44X after Se annealing. We believe that these results demonstrate a robust method for mitigating unintentional doping in a promising class of materials for thermoelectric applications.¹

1. Chen, J.; Hamann, D. M.; Choi, D. S.; Poudel, N.; Shen, L.; Shi, L.; Johnson, D. C.; Cronin, S. B., Enhanced Cross-plane Thermoelectric Transport of Rotationally-disordered SnSe2 via Se Vapor Annealing. Nano Letters 2018.