Effect of Growth Temperature on the Interface Quality of Quantum Cascade Structures

The interface quality of Superlattices significantly affects material and Quantum Cascade Laser (QCLs) device performance. This paper investigates the growth of high differential gain structure QCLs by molecular beam epitaxy (MBE) and studies the changes in superlattice quality under different temperature gradients for InGaAs/lnA1As materials. In this work, A series of temperature gradients with a broad range were applied to InGaAs and InAlAs. The results show that when the growth temperature of InGaAs is 520°C and the growth temperature of InAlAs is 530°C, the QCL superlattice growth quality has the best performance. High-resolution X-ray diffraction (HRXRD) was adopted to measure the composition and growth rate of the superlattice layers. High-resolution transmission electron microscopy (HRTEM) indicates that good material quality with no dislocations exist between the InGaAs/lnAlAs layers at the optimal growth temperature and clear and straight interfaces. The results indicate that InGaAs is more sensitive to temperature variations. The findings from this study have the potential to guide the fabrication of high-quality devices.