Constriction Resistance and Current Crowding in Electrically Pumped Semiconductor Nanolasers with the Presence of Undercut and Sidewall Tilt

We evaluate the constriction resistance and current crowding in nanolasers using the finite-element method based calculations. We examine both the vertical contact and horizontal contact structures, representing the typical top contact and bottom contact of nanolasers, respectively. We find that, in general, constriction resistance and the degree of current crowding in the bottom horizontal contact in nanolasers are much larger than those in the top vertical contact. For both contacts, constriction resistance and, therefore, the degree of current crowding increase as the nanolaser radius decreases, the amount of undercut increases, or the angle (either positive or negative) of the sidewall tilt increases. The location where most current crowding and most Joule heating occur is identified. The results may provide insights into the design optimization of nanolasers.