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比较了蓝光LED和LD的辐射量子效率随电流密度变化的趋势。LED在低电流密度时具有很高的辐射量子效率,并且在电流密度为24.4A/cm~2时达到了峰值效率,随着电流密度的增大,其量子效率会急剧下降;LD在电流密度低于出光阈值时辐射量子效率为零,待达到出光阈值后迅速上升并在电流密度为4.85×10~3 A/cm~2时超越LED。分析表明,LED效率骤减是由于自身的发光机理限制了辐射速率的提升;LD受激辐射发光机理恰好弥补了LED的不足,其辐射量子效率受非辐射复合速率的影响较小。结果表明,LD具有高电流密度下高辐射量子效率的特性。
The radiation quantum efficiency of blue LED and LD is compared with the current density. The LED has high radiation quantum efficiency at low current density and reaches peak efficiency at a current density of 24.4 A / cm ~ 2. With the increase of the current density, the quantum efficiency of the LED decreases sharply. At the current density The quantum efficiency of radiation below zero is lower than that of the light-emitting threshold. After reaching the light-emitting threshold, the quantum efficiency rises rapidly and surpasses the LED at a current density of 4.85 × 10 ~ 3 A / cm ~ 2. The analysis shows that the sharp decrease of LED efficiency is due to its own luminescent mechanism which limits the increase of radiation rate. The LD stimulated emission mechanism just makes up for the deficiency of LED, and its radiation quantum efficiency is less affected by the nonradiative recombination rate. The results show that LD has high radiation quantum efficiency at high current densities.