Valley relaxation of resident electrons and holes in a monolayer semiconductor: Dependence on carrier density and the role of substrate-induced disorder
Jing Li, M. Goryca, K. Yumigeta, H. Li, S. Tongay, S. A. Crooker
Abstract
Analogous to the keen interest in electron, hole, and exciton spin relaxation during the early days of semiconductor spintronics, measurements of valley relaxation in monolayer transition-metal dichalcogenide (TMD) semiconductors such as WSe2 are currently a focus of attention for potential applications in valleytronics. For many notional valleytronic devices, the important parameter is the intrinsic valley relaxation time of the resident electrons and holes that exist in n-type and p-type TMD monolayers. Using optical methods, the authors determine these timescales as a systematic function of carrier density, and study the (important) role of the underlying substrate. Microsecond-long valley relaxation of carriers is revealed at low densities.