Understanding the Nature of Crystallographic Bonds by Establishing the Correlation between Ion-Pair Chemistry and Their Separation in Detector Space

The occurrence of multi-hit events and the separation distance between multi-hit ion pairs field evaporated from III-nitride semiconductors can potentially provide insights on neighboring chemistry, crystal structure, and field conditions. In this work, we quantify the range of variation in major III-N and III-III ion-pair separation to establish correlations with bulk composition, growth method, and ion-pair chem- istry. The analysis of ion-pair separation along the AlGaN/GaN heterostructure system allows for comparison of Ga-N and Ga-Ga ion-pair separation between events evaporated from pure GaN and Al0.3Ga0.7N. From this, we aim to define a relative measure for the bond length of ion pairs within an AlGaN/GaN hetero structure. The distributions of pair separation revealed a distinct bimodal behavior that is unique to Al-N-2(+) ion pairs, suggesting the occurrence of both co-evaporation and molecular dissociation. Finally, we demonstrated that the two modes of ion-pair events align with the known variation in the surface electric field of the AlGaN(0001) structure. These findings demonstrate the utility of atom probe tomography in studying the crystallographic nature of nitride semiconductors.

Automated summary

This work investigates the correlation between the separation distance of ion pairs evaporated from III-nitride semiconductors and bulk composition, growth method, and ion-pair chemistry. The analysis of ion-pair separation in the AlGaN/GaN heterostructure system reveals a distinct bimodal behavior unique to Al-N-2(+) ion pairs, indicating both co-evaporation and molecular dissociation. Furthermore, it is found that the two modes of ion-pair events align with the known variation in the surface electric field of the AlGaN(0001) structure.