Monte Carlo simulation of extraction barrier width effects on terahertz quantum cascade lasers

The effect of extraction barrier width on the performance of a resonant-phonon terahertz quantum cascade laser is studied using the ensemble Monte Carlo method. The width of extraction barrier is varied from 48 to 33 angstrom with a stepsize of -3 angstrom. The calculated threshold current density increases monotonously from 436 to 1054 A/cm(2) with decreasing extraction barrier width, while the peak gain shows nontrivial behavior. These findings agree well with an experimental study. The simulation results suggest an optimal extraction barrier width of 36 angstrom for peak gain and for the best temperature performance. (C) 2008 American Institute of Physics.