Fundamental limits to far-infrared lasing in Auger-suppressed HgCdTe quantum wells

TL;DR

This paper demonstrates that HgCdTe quantum wells can suppress Auger recombination, enabling efficient far-infrared lasing at ~50 μm with low threshold currents, advancing terahertz laser technology.

Contribution

It introduces a microscopic theory showing how topological states in HgCdTe QWs suppress Auger processes, facilitating long-wavelength lasing at liquid nitrogen temperatures.

Findings

Lasing feasible down to ~50 μm wavelength.

Threshold currents are two orders of magnitude lower than existing lasers.

Experimental data aligns with the theoretical predictions.

Abstract

A challenge of bridging the terahertz gap with semiconductor lasers faces an inevitable problem of enhanced non-radiative Auger recombination with reduction of photon energy. We show that this problem can be mitigated in mercury-cadmium-telluride quantum wells (HgCdTe QWs) wherein the Auger process is suppressed due to formation of quasi-relativistic electron-hole dispersion imposing strong energy-momentum restrictions on recombining carriers. Such dispersion is formed upon interaction of topological states at the two QW interfaces. We characterize the lasing properties of HgCdTe QWs quantitatively by constructing a microscopic theory for recombination, absorption, and gain, and show the feasibility of lasing down to ~ 50 $\mu$m at liquid nitrogen temperature with threshold currents two orders of magnitude lower than in existing lasers. Our findings comply with recent experimental data on stimulated far-infrared emission from HgCdTe QWs and show the directions toward achievement of maximum possible lasing wavelength.