Domain free high field superlattice transport

TL;DR

This paper reports the first realization of a superlattice-shunt system that maintains homogeneous electric field conditions, enabling Bloch oscillator operation and effective GHz excitation, by combining undoped superlattice and 2D surface superlattice channels.

Contribution

The authors demonstrate a novel superlattice-shunt configuration using cleaved-edge-overgrowth, confirming predicted I-V characteristics and GHz excitation capabilities.

Findings

Confirmed the long-predicted I-V characteristic of superlattices in homogeneous electric fields.

Demonstrated GHz regime excitation in the superlattice-shunt system.

Validated the effectiveness of the shunt approach under external AC electric fields.

Abstract

The fundamental condition for operating a superlattice (SL) as a Bloch oscillator is a homogeneous electric field alignment under large applied bias. This can be done by combining the nonlinear miniband transport channel with a parallel shunt channel, connected through lateral transport. We report here about the first realization of such a SL-shunt system. With the cleaved-edge-overgrowth (CEO) method we combine an undoped superlattice, which acts as the shunt, with a two-dimensional (2D) cleaved-edge surface superlattice channel. Our results confirm the long predicted current-voltage-characteristic (I-V) of a SL in a homogeneous DC electric field. Excitation experiments in the GHz regime show that our shunt approach also works in the presence of an external AC electric field.