In-situ accumulated stress measurements: application to strain balanced quantum dots and quantum posts

TL;DR

This paper demonstrates the use of in-situ accumulated stress monitoring to optimize strain balancing in quantum dot and quantum post fabrication, highlighting the importance of process kinematics and substrate temperature for high-quality nanostructures.

Contribution

It introduces an in-situ stress measurement technique for strain balancing, emphasizing the role of process dynamics and temperature in improving nanostructure quality.

Findings

Substrate temperature significantly affects strain compensation.

In-situ measurements enable fabrication of longer quantum posts.

Relaxation processes can be suppressed to enhance material quality.

Abstract

In this work we use the in-situ accumulated stress monitoring technique to evaluate the evolution of the stress during the strain balancing of InAs/GaAs quantum dots and quantum posts. The comparison of these results with simulations and other strain balanced criteria commonly used indicate that it is necessary to consider the kinematics of the process, not only the nominal values for the deposited materials. We find that the substrate temperature plays a major role on the compensation process and it is necessary to take it into account in order to achieve the optimum compensation conditions. The application of the technique to quantum posts has allowed us to fabricate nanostructures of exceptional length (120 nm). In situ accumulated measurements show that, even in shorter nanostrcutures, relaxation processes can be inhibited with the resulting increase in the material quality.