固态照明用蓝光LED和LD辐射量子效率与电流密度的比较研究

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24.4 A/cm2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4.85×103 A/cm2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.

Comparative Study on the Current Density and Radiation Quantum Efficiency of Solid State Lighting Blue LED&LD

The relation between radiation quantum efficiency and current density of blue light LED&LD was studied. LED radiation quantum efficiency is very high at low current density, and reaches the peak value when the current density is 24.4A/cm2. But the quantum efficiency declines sharply as the current density increases. LD radiation quantum efficiency is zero when the current density is lower than the threshold, but increases rapidly after the current density reaches the threshold, and surpasses that of LED when the current density reaches 4.85×103A/cm2. Analysis shows that the huge drop of LED efficiency is caused by its own light-emitting mechanism, which restricts the promotion of radiation rate. The stimulated radiation emitting mechanism of LD makes up for the deficiency of LED, and the rate of no-radiative recombination has a relatively low impact on the radiation quantum efficiency. The results show that LD has characteristics of high radiation quantum efficiency under high current density.