A Study of Efficiency Droop Phenomenon in GaN-Based Laser Diodes before Lasing

Carrier recombination behavior in c-plane GaN-based laser diodes (LDs) is numerically investigated by using the commercial software LASTIP. It is found that efficiency droop phenomenon does exist in GaN-based LDs before lasing, which is confirmed by experimental results. However, the current density corresponding to the peak efficiency of GaN-based LDs before lasing, J_max, is nearly 40 A/cm², which is much lower than that reported by other studies. The reported J_max, measured from the cavity facet side is modulated by the absorption of quantum wells, which shifts the J_max to a higher value. In addition, the currents due to various recombinations are calculated. It is found that Auger recombination affects the threshold current greatly, but it only plays a small role at high current injection levels.