Effect of Undercut Etch on Performance and Fabrication Robustness of Metal-Clad Semiconductor Nanolasers

We use optical, thermal, and electrical simulation to evaluate the effects of using varying amounts of undercut etch on wavelength-scale and subwavelength metal-clad semiconductor nanolasers (MCSELs). We find that as MCSEL diameter decreases, the optical performance becomes more sensitive to slight amounts of sidewall tilt. A modest amount of undercut (25%) dramatically improves the optical performance, reducing modal threshold gain to 100 cm^-1 or less for lasers with core radius of 225, 550, or 775 nm, even in the presence of significant sidewall tilt (20° gain sidewall or ±8° pedestal sidewall tilt). Finally, we examine the effects of the increased undercut on nanolaser thermal performance and find that the increased resistive heating is insignificant near threshold, even for subwavelength nanolasers.