Carrier multiplication in graphene under Landau quantization

TL;DR

This paper demonstrates that applying Landau quantization to graphene significantly enhances carrier multiplication, which could improve photovoltaic efficiency by enabling tunable control over charge carrier generation.

Contribution

It introduces a novel approach using Landau quantization to achieve tunable and enhanced carrier multiplication in graphene, supported by microscopic density matrix calculations.

Findings

Significant carrier multiplication observed under Landau quantization.

Carrier multiplication tunable via magnetic field, temperature, and pump fluence.

Potential for improved photovoltaic device efficiency.

Abstract

Carrier multiplication is a many-particle process giving rise to the generation of multiple electron-hole pairs. This process holds the potential to increase the power conversion efficiency of photovoltaic devices. In graphene, carrier multiplication has been theoretically predicted and recently experimentally observed. However, due to the absence of a bandgap and competing phonon-induced electron-hole recombination, the extraction of charge carriers remains a substantial challenge. Here we present a new strategy to benefit from the gained charge carriers by introducing a Landau quantization that offers a tunable bandgap. Based on microscopic calculations within the framework of the density matrix formalism, we report a significant carrier multiplication in graphene under Landau quantization. Our calculations reveal a high tunability of the effect via externally accessible pump fluence, temperature, and the strength of the magnetic field.