Vertical transport in superlattices

TL;DR

This paper investigates the vertical electron transport in three-dimensional superlattices, exploring effects like magnetoresistance, quantum miniband bending, interface imperfections, and complex high-field domain structures, with results aligning with experimental data.

Contribution

It provides a comprehensive quantum mechanical analysis of vertical transport phenomena in superlattices, including new insights into magnetoresistance and high-field domain structures.

Findings

Collisionless transverse magnetoresistance effect identified

Magnetic field bends minibands, classifying states into Landau and Stark types

Interface roughness correlation length measurable via magnetoresistance

Abstract

All the principal results of this work concern the vertical transport in generic three dimensional superlattices. In the 1st chapter we make an historical introduction, then we discuss the geometry of the problem, and the physical parameters associated with structure of electron minibands and strength of external fields. We found the effect of collisionless transverse magnetoresistance, and we discuss it in the 2nd chapter. This effect is similar to collisionless Landau damping in a plasma and we utilize the same name. In the 3rd chapter we provide quantum mechanical reasons for the above effect; we show how a magnetic field bends narrow superlattice minibands, and we classify the states into Landau-type and Stark-type. In the 4th chapter we compute longitudinal magnetoresistance of superlattices due to the imperfections of the interfaces. Correlation length of the interface roughness can be measured independently by this method. In the 5th chapter we discuss the current-voltage characteristic of superlattice when an electric field destroys the one-miniband transport. We found that the structure of the high-field domains in the superlattices is complicated, but can be described analytically with great accuracy. This structure reveals itself in the details of the current-voltage characteristics. All our results are consistent with existing experiments, and we make careful comparison of theoretical predictions and experimental results in all chapters.