Epitaxial growth and real-time characterization of self-assembled quantum dots using reflection high energy electron diffraction.

摘要

In this work we undertake a detailed characterization of self-assembling quantum dots (QD) of InAs/GaAs (001), archetype material system, using reflection high energy electron diffraction (RHEED). Our purpose is to develop RHEED as a practical tool in determining the complete morphology of self-assembled nano-structures real time during growth. Our analysis is carried out in two stages; first, a theoretical modeling combining calculation of atomistic strain distribution in the InAs/GaAs quantum dots and diffraction pattern was performed. RHEED images are analyzed for different QD sizes and shapes. The features in RHEED images are identified and assigned to different QD structural properties. The facet orientations are extracted by the angle between RHEED chevrons. The dot height is correlated to the period of RHEED intensity fringes along chevron tails. Second, an experimental investigation was undertaken toward demonstrating the applicability of RHEED for real time in situ monitoring of structural properties of self-assembled quantum dots. Independent experimental validations are provided using atomic force microscopy (AFM) and photo luminescence (PL) measurements. The possibility of real time during growth diagnosis of self-assembled quantum dots' structural properties and their temporal evolution using RHEED is demonstrated.