InGaAs/AlInGaAs THz quantum cascade lasers operating up to 195 K in strong magnetic field

Federico Valmorra,Keita Ohtani,Jérôme Faist,Mattias Beck,Giacomo Scalari

doi:10.1088/1367-2630/17/2/023050

Abstract

Terahertz quantum cascade lasers based on InGaAs wells and quaternary AlInGaAs barriers were measured in magnetic field. This study was carried out on a four-quantum-well active-region design with photon energy of 14.3 meV processed with both Au and Cu waveguides. The heterostructure operates up to 148 K at B = 0 T in a Cu waveguide. The complete magneto-spectroscopic study allowed the comparison of emission and transport data. Increasing the magnetic field, the low effective mass of the InGaAs wells allowed us to reach the very strong confinement regime. At B = 12 T, where the cyclotron transition is almost resonant with the LO-phonon, we recorded a maximum operating temperature of 195 K for the devices with Cu waveguide. Additional lasing at 5.9 meV was detected for magnetic fields between 7.3 and 7.7 T.

Highlights

Terahertz quantum cascade lasers based on InGaAs wells and quaternary AlInGaAs barriers were measured in magnetic field
The terahertz (THz) spectral range is regarded with ever increasing interest for sensing, imaging and spectroscopy applications and quantum cascade lasers (QCLs) represent a primary semiconductor-based, electrically pumped source that can cover its range.[1,2,3,4,5,6]
An alternative option comes from QCLs based on quaternary AlInGaAs barrier material.[10,11]

Summary

Introduction

Terahertz quantum cascade lasers based on InGaAs wells and quaternary AlInGaAs barriers were measured in magnetic field. The J-V characteristics of the QCLs were recorded along with the laser emitted intensity (L) as a function of the magnetic field applied along the growth axis within the temperature range 4-200 K. This directly points at a lower losses’ level for the Cu-Cu waveguide with respect to the Au-Au. Several oscillations in the threshold current density and consequent variations in the emitted light are present in the colour maps, especially for the low B-field region.

Results

Conclusion