脊形InGaN激光器的温度分布及其对器件特性的影响

利用含时二维热传导模型分析了蓝宝石衬底上生长、制作的脊形InGaN激光器内波导层的温度分布和时间演化规律.由于较大的阈值电流和电压以及较差的衬底导热性能,脊形下波导层内会产生较高温升并在脊形内外形成较大的温度台阶.由于脊形波导的弱自建波导特性,这一温度台阶会对侧向模式的限制产生较大的影响.短脉冲工作下的时间分辨L-I测试以及时间分辨远场和光谱测试结果显示,脊形内外的温度台阶会改善波导对高阶模的限制,导致器件的阈值电流下降,斜率效率升高.而有源区的温升又会导致斜率效率的严重下降.

Temperature Distribution in Ridge Structure InGaN Laser Diodes and Its Influence on Device Characteristics

Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model. A high temperature in the waveguide layer and a large temperature step between the regions under and outside the ridge are generated due to the poor thermal conductivity of the sapphire substrate and the large threshold current and voltage. The temperature step is thought to have a strong influence on the characteristics of the laser diodes. Time-resolved measurements of light-current curves, spectra, and the far-field pattern of the InGaN laser diodes under pulsed operation are performed. The results show that the thermal lensing effect improves the confinement of the higher order modes and leads to a lower threshold current and a higher slope efficiency of the device while the high temperature in the active layer results in a drastic decrease in the slope efficiency.