GaN基蓝光LED中光子晶体对提取效率及发光偏振态的影响

为了提高氮化镓基蓝光发光二极管的发光提取效率,在其电流扩展层上生长光子晶体.讨论了光子晶体结构周期、刻蚀深度和占空比参数与提取效率的关系,并采用时域有限差分法进行模拟计算.结果表明在晶格周期为300nm、占空比为60%和刻蚀深度为200nm的条件下,生长光子晶体结构后,氮化镓基蓝光发光二极管的提取效率提升了27.93%.研究了激励源在光子晶体晶格周期内位置变化对提取效率的影响,拟合得到更符合实际物理意义的氮化镓基蓝光发光二极管发光提取效率函数.利用等效折射率理论和法布里-珀罗薄膜干涉模型解释了氮化镓基蓝光发光二极管中TE模和TM模偏振之间提取效率的差异,数值仿真得到最大差异值为1.442倍,从而获得高偏振对比度光源.用该结构参数制备的发光二极管器件应用于液晶显示背光源,可提高液晶显示的能耗效率.

Extraction Efficiency and Polarization Induced by Photonic Crystal Structure on GaN-based Blue LED

In order to improve the extraction efficiency,photonic crystal was generated on the ITO current spreading layer of GaN-based blue LED.By using the finite difference time domain method,the relationship between the structural parameters of photonic crystal and extraction efficiency was simulated.The optimization enhencement results of 27.93 ％ were obtained on the photonic crystal with cycle of 300nm,duty of 60％ and etching depth of 200nm.Point source location varied in a photonic crystal lattice cycle was investigated in the finite difference time domain method simulation to get the correction extraction efficiency by fitting the simulations.Using the effective medium theory to get the effective refractive indexes,extraction efficiencies of both TE and TM mode polarization were calculated according to Fabry-Perot thin-film interference model.The maximum difference between the TE and TM light out-coupling was 1.442,and the light source with high polarization contrast was obtained.The proposed device can be applied in the LED back-light to improve the energy consumption of the liquid crystal display.