InGaAs/AlInGaAs THz quantum cascade lasers

InGaAs/AlInAs/InP is a successful semiconductor material for operation of high performance mid-infrared quantum cascade lasers (QCLs) [1, 2]. However, in the THz region, a thin AlInAs barrier is required due to its high conduction band offset energy (530 meV) and is believed to limit a laser performance since subband position would be very sensitive to the layer thickness. In this work, we use a different barrier material to overcome this disadvantage: quaternary alloy AlInGaAs. Lattice matched AlInGaAs barriers are implemented in a bound-to-continuum four quantum wells active structure [3]. Al and Ga composition in the quaternary barrier is selected so as to provide the conduction band offset energy of (A) 150 meV and (B) 120 meV.