Analysis of low-threshold optically pumped III-nitride microdisk lasers

Low-threshold lasing under pulsed optical pumping is demonstrated at room temperature for III-nitride microdisks with InGaN/GaN quantum wells on Si in the blue spectral range. Thresholds in the range of $18 kW/cm2$ have been achieved along with narrow linewidths of 0.07 nm and a large peak-to-background dynamic of 300. We compare this threshold range with the one that can be calculated using a rate equation model. We show that thresholds in the few $kW/cm2$ range constitute the best that can be achieved with III-nitride quantum wells at room temperature. The sensitivity of lasing on the fabrication process is also discussed.