Y.J. Sung

High-Performance Blue InGaN Laser Diodes With Single-Quantum-Well Active Layers

The authors report on the high-performance blue laser diodes (LDs) with an emission wavelength of ~448 nm employing InGaN single-quantum-well (QW) active layers. At 100-mW continuous-wave (CW) output power, operation current and voltage are, respectively, 150 mA and 5.3 V, corresponding to the wall plug efficiency of >12%, a record value for the single-mode InGaN LDs with blue wavelengths. The single QW blue LD showed normal temperature dependence of light output-current curves with the characteristic temperature of 170 K. In addition, we demonstrate a high level of catastrophic optical damage of >300 mW and long device lifetime under CW operation condition at room temperature.

Single-mode blue-violet laser diodes with low beam divergence and high COD level

We demonstrate GaN-based high-power single transverse-mode laser diodes (LDs) emitting at 405 nm. LD structures are designed to exhibit a high level of catastrophic optical damage and small beam divergence angle. By the control of refractive index profiles, we achieved a vertical beam divergence angle of as low as 17.5/spl deg/ and maximum output power of as high as 470 mW under continuous-wave operation condition. In addition, nearly fundamental transverse-mode operation is demonstrated up to 500-mW pulsed output power by far-field investigation.

Carrier Transport Mechanism of Pd/Pt/Au Ohmic Contacts to p-GaN in InGaN Laser Diode

The dependence of contact resistivity on the carrier concentration for the non-alloyed Pd contacts on p-GaN and the temperature dependence measurements of sheet resistivity of p-GaN suggest that carrier transport at the interface between the contact and the p-GaN would be dominated by deep level defect band, rather than the valence band. Based on these results, in order to reduce the operating voltage of the InGaN laser diode (LD), we designed a p-GaN:Mg contact layer, where the ohmic metals are contacted, and optimized the p-GaN contact layer.

High-power blue-violet laser diodes with improved beam divergence and high COD level

GaN-based laser diodes for 405 nm high-power applications are demonstrated. By decreasing the Al concentration of n-cladding layers, the vertical divergence angle was reduced to <18/spl deg/ and the average COD level was increase to >300 mW.