Application of Exit-Plane Wave Function Images in High-Resolution Transmission Microscopy for Compositional Analysis of III-V Semiconductor Interfaces

Abstract

Existing methods based on high-resolution transmission electron microscopy (HRTEM) for compositional analysis of III-V semiconductor interfaces are applicable only to ternary systems [1][2][3][4]. Furthermore, they require optimal specimen-thickness and imaging conditions which depend on the material system under investigation. In this work we investigate the applicability of exit-plane wave function (EPWF) images, retrieved from HRTEM images, for quantitative chemical analysis of III-V semiconductor interfaces. By using the focus variation technique for EPWF retrieval [5] in combination with factorial analysis of correspondence for quantitative analysis [6], we show that compositional profiles along the group-III and group-V sublattices can be independently extracted. The present approach is more general, enabling compostional analysis of other III-V semiconductor heterostructures, such as InGaSb/InAs and InGaP/GaAs, which exhibit intermixing in both group-III and group-V sublattices. Application of the proposed method to the analysis of interfaces in epitaxially grown Al x Ga (1-x) As/GaAs and In x Ga (1-x) Sb/InAs heterostructures yielded compositional sensitivities with standard deviations equal to 0.06 (x Al-Ga )and 0.08 (x In-Ga and x As-Sb ), respectively. The validity of this approach is verified by an image simulation study performed on model interfaces with abrupt and linear grading in the interface composition profiles.