Abstract

Interwell carrier distribution is a process of major importance for the operation of multiple quantum well (MQW) lasers. Previous studies have shown that in InGaAsP as well as in InAlGaAs heterostructures increased valence band barrier height influences hole transport over the MQW barriers [1]. On the other hand, for a good high temperature performance good electron confinement is needed. In this work we examine a novel approach to improve high temperature performance in the InGaAsP lasers by adding aluminium to the barrier, which allows to increase conduction band offset. To find optimal heterostructure parameters, different barrier material compositions have been examined in structures with InGaAsP compressively strained wells and tensile strained InGaAlAsP barriers. The MQW structures were fabricated by low pressure MOVPE. They contained four period transport-MQWs emitting at 1.3 μm. The interwell carrier transport was measured by time resolved photoluminescence (PL) in a specially designed structures (Fig. 1), in which the carriers are mainly photogenerated in the top InP layer and their transport detected by measuring PL from a detector well with a smaller band gap. The PL intensity decay from the InP cap layer is exponential, approximated with exp(-t/τ₁), with a decay time τ₁ measured to be in the range from 33 to 56 ps. The PL intensity rise from the detector well is approximated with 1-exp(-t/τ₂), and the rise times τ₂ changing from 47 to 266 ps.

© 2000 IEEE