Vertical Transport, Tunneling Cyclotron Resonance, and Saturated Mini-Band Transport in Semiconductor Superlattices

Abstract

The focus of the early vision of Esaki and Tsu (1970), on vertical transport in artificial semiconductor superlattices, foresaw engineered bands tuctures with narrow mini-bands and forbidden mini-gaps that would lead to novel transport physics and devices. The phenomenon that captured their attention was Bloch oscillation, a phenomenon that can be readily understood in terms of saturated band transport in a narrow conduction band (Ktitorov, 1972). The key role played by the superlattice is the production of narrow mini-bands that can be saturated by modest electric fields and current density, which in turn would lead to differential negative resistance, gain and eventually Bloch oscillations. Saturated transport is the key phenomena and is a unique feature of miniband transport. Here we describe cyclotron resonance experiments that directly probe mini-band transport. Saturated band transport manifests itself as a saturation of the cyclotron resonance frequency in strong magnetic fields.