Ridge‐geometry InGaN multi‐quantum‐well‐structure laser diodes

Stripe‐ and ridge‐geometry in InGaN multi‐quantum‐well (MQW)‐structure laser diodes (LDs) were fabricated on sapphire substrates with (1120) orientation (A face). The ridge‐geometry InGaN MQW LDs showed strong stimulated emission at a wavelength of 411.3 nm under a pulsed current injection of 199 mA at room temperature. The differential quantum efficiency per facet and the threshold current of ridge‐geometry LDs were 30% and 180 mA, respectively. The laser threshold current density was 3 kA/cm2. These values were greatly improved in comparison to those of stripe‐geometry LDs. The characteristic temperature of the threshold current was around 185 K.