红外子带间量子级联激光器的短波极限

SHORTWAVE LIMIT OF INFRARED INTERSUBBAND QUANTUM CASCADE LASERS '

从理论上探讨了红外子带间量子级联激光器向短波段发展的可能性及其根本性困难 ,用模型固体理论的基本假设、应变能带理论、非抛物性能带的经验二带模型、传播矩阵和分层逼近法 ,分析计算了以 Ga Sb为衬底的In As/Al Sb,In As/Al0 .6 Ga0 .4Sb,和以 In P为衬底的 In0 .5 3 Ga0 .4 7As/In0 .5 2 Al0 .4 8As的带阶 ,及其所组成的量子阱在加和不加电场作用下的束缚态 .发现其导带最大子带边能量差不可能超过其阱深的 56%～ 62 % ,而且受到导带间接能谷的限制而进一步减小 .设计提出了迄今发射最短波长为 2 .88μm的由 2 5个周期共 2 50个耦合量子阱组成、外加电场为 10 0 k

The feasibility and fundamental difficulty in developing the infrared intersubband quantum cascade lasers in shorter wavelength range were discussed theoretically. The band offsets of InAs/AlSb on GaSb substrate, InAs/Al 0.6 Ga 0.4 Sb on GaSb substrate, and In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As on InP substrate, and the confined states of their quantum wells with and without an applied electric field were analyzed and calculated by using the fundamental assumption of model solid theory, strained band structure theory, empirical two band model for non parabolic band, and methods of propagation matrix and laminar approach. It was found that the greatest energy difference between subband edges can not exceed 56~62% of the conduction band offset, and will be decreased further by the indirect valley. A designed structure of intersubband quantum cascade laser consisting of 250 coupled quantum wells in 25 periods under electric field 100kV/cm for emitting the shortest wavelength 2.88μm was proposed.