GaN垒层厚度渐变的双蓝光波长发光二极管

Dual-blue Wavelength Light-emitting Diodes Based on Varied GaN Barrier Thickness

针对单蓝光波长芯片与Y3Al5O12∶Ce3+黄光荧光粉封装白光发光二极管存在显色性不足的问题,提出了采用双蓝光波长芯片激发Y3Al5O12∶Ce3+黄光荧光粉实现高显色性白光发射法,并分析了其可行性.利用金属有机化学气相沉积系统在(0001)蓝宝石衬底上顺序生长两个In0.18Ga0.82N/GaN量子阱和两个In0.12Ga0.88N/GaN量子阱的双蓝光波长发光二极管,并对不同GaN垒层厚度的双蓝光波长发光二极管的光电性能进行分析,结果表明沿n-GaN到p-GaN方向减小GaN垒层厚度能实现双蓝光发射,并有较好的发光效率.交流阻抗谱结果显示相关双蓝光波长发光二极管可以用一个电阻Rp与电容Cp并联后与一个Rs串联电路来模拟,GaN垒层变化能调节并联电阻和电容,对串联电阻没有影响.此外,基于垒层减小的双蓝光波长芯片激发Y3Al5O12∶Ce3+荧光粉实现了高显色指数的白光发射.

Due to low color rendering index of white light-emitting diodes based on packing of single-blue wavelength chip and Y3A15012 ： Ce3＋ yellow phosphors, using dual-blue wavelength chip, Y3A15012 ： Ce3＋ yellow phoshpor is proposed to realize high color rendering index white emission, and feasibility of the method is analyzed. Dual-blue wavelength light-emitting diodes based on two pairs of In0.18 Ga0. sz N/GaN quantum-well and two pairs of In0.,2 Ga0.88 N/GaN quantum-well structure were grown sequentially on the same sapphire substrate by metal-organic chemical vapor deposition. Optoelectronic properties of dual-wavelength light-emitting diodes with different GaN barrier thicknesses were also studied. The experimental results indicate that efficient dual-blue-wavelength emission and higher luminescent efficiency are realized from light- emitting diodes by reducing GaN barrier thickness from n-GaN to p-GaN. The a. c. impedance spectroscopy can be explained in terms of the equivalent series circuit model of a set of parallel resistor-capacitor RpCp and a resistor Rs for the dual-blue wavelength light-emitting diodes. Varied GaN barrier thickness can tune parallel resistor and capacitor while it has no effect on series resistor. In addition, Y3A15012 ＂ CC＋ phosphor-converted white light emission with high color rendering index is achieved by use of dual-blue emitting active regions from reducing barrier thickness.