光电耦合对InGaN/GaN量子阱光学性能的影响

围绕高性能GaN基垂直腔面发射激光器(VCSELs),设计了两种具有不同光电耦合强度的InGaN/GaN量子阱(QWs)样品,研究了它们的光学性质。样品A在腔模的两个波腹处各放置两个InGaN耦合量子阱,而样品B在腔模的一个波腹处放置5个InGaN耦合量子阱。计算表明样品A具有较大的相对光限制因子1.79,而样品B为1.47。光学测试发现样品A有着更高的内量子效率(IQE)和更高的辐射复合效率。使用两种样品制作了光泵VCSEL结构,在光激发下实现激射,其中基于样品A的VCSEL有着更低的激射阈值。结果表明有源区结构会显著影响量子阱与光场的耦合作用、外延片的内量子效率、辐射复合寿命和VCSEL激射阈值,同时也说明样品A的有源区结构更有利于制作低阈值的VCSEL器件。

Influence of Photo-electron Coupling on Optical Properties of InGaN/GaN Quantum Wells

Toward high performance GaN-based vertical cavity surface emitting lasers(VCSELs),we designed two types of InGaN/GaN coupled quantum wells(QWs)with different photo-electron interaction strengths,and studied their optical properties.In sample A,two sets of QWs are located at two antinodes of the optical field with two coupled QWs in each set.While in sample B,one set of QWs is located at one antinode of the optical filed with five coupled QWs.The relative optical confinement factors are calculated to be 1.79 and 1.47 for samples A and B,respectively.Optical measurements revealed that sample A has higher internal quantum efficiency(IQE)and higher radiative recombination efficiency.VCSELs fabricated by using sample A are featured with lower threshold pumping energy compared with the device fabricated from sample B.These results demonstrated that the structure of QWs will influence the photo-electron interaction,the IQE,the radiative efficiency of materials,and the threshold of VCSELs.In our case,structure of sample A is better than sample B.