Tall-barrier terahertz quantum cascade lasers

Abstract

A terahertz quantum cascade laser is presented in which selectively placed pure AlAs barriers are used to reduce parasitic leakage currents to the conduction band continuum. The design is demonstrated to have improved temperature performance over a regrowth of the current T [subscript max] ∼ 200 K record holder (181 K vs. 175 K). Strangely, it fails to lase below ∼70 K, which we attribute to negative differential resistance (NDR) prior to threshold. A subsequent design using only AlAs barriers failed to lase, the reason for which we posit to be either early NDR or excessive interface roughness scattering.National Science Foundation (U.S.)United States. National Aeronautics and Space Administratio