Network Analyzer for Carrier Lifetime Measurements in Mid-IR semiconductor Lasers

摘要

The Hewlett-Packard 8722D microwave network analyzer and cables that were obtained under the Grant have been used to perform the first electrical measurements of the carrier lifetime, Tau(sub d), and radiative recombination in quantum dot LEDs. Our analysis shows that the ground and excited quantum dot energy states exhibit significantly different radiative recombination rates. We have measured Tau(sub d) as a function of current density for quantum dot LED samples using the microwave equipment and used this data to calculate the functional relationship between the carrier lifetime, carrier density, and radiative efficiency. The results indicate that carrier filling on the different dot energy levels has a strong influence on the radiative behavior of the devices and that the radiative rate coefficient, B, for different QD levels can vary considerably.