Who needs an electrical back-contact after all?

Abstract

Atomic force microscopy (AFM) is essential for nanoscale material characterization, yet its electrical modes are fundamentally constrained by the requirement of a physical back-contact (BC). The sample under study often requires complex and destructive sample preparation, such as cleaving, metallization, and the use of conductive adhesives, to close the electrical circuit. Due to their destructive nature and applicability only to small coupon samples, electrical AFM modes are generally incompatible with contamination-controlled, automated, in-line semiconductor metrology. To overcome these barriers, we introduce electron-beam excited AFM (EB-AFM). In this configuration, a low-energy electron beam is focused near the AFM probe to replace the physical BC, acting as a remote and reconfigurable electrode. We elucidate the fundamental parameters governing this electron-beam stimulation and demonstrate contact-free electrical mapping on 2D materials, III–V semiconductors, and fully integrated device structures. Our results show that EB-AFM achieves defect contrast and sensitivity comparable to conventional methods without requiring any sample modification. By eliminating the back-contact constraint and enabling wafer-scale compatibility, EB-AFM provides a pathway toward non-destructive, fully automated electrical metrology, thereby broadening the scope of nanoscale device characterization.