Effects of extraction barrier width on performance of terahertz quantum-cascade lasers

Experimental results are presented on the effects of extraction barrier on the performance of resonant phonon terahertz quantum-cascade lasers. The extraction barrier is varied from 48 to 39 Å in an otherwise identical 3.4 THz laser structure. It is found that, when the extraction barrier width decreases from 48 to 39 Å, the threshold current density at 10K increases monotonously from 900 A/cm2 to 1.4 kA/cm2, and the maximum lasing temperature increases from 95 to 110K. No optimum extraction barrier width was found for maximum lasing temperature.