Advanced characterization of atomic terraces and electronic topography of graphite using STM in constant current and constant height modes

Abstract

This study presents a high-resolution scanning tunneling microscopy analysis of highly ordered pyrolytic graphite, aimed at quantitatively characterizing atomic-scale surface features using both constant-current and constant-height imaging modes. Building upon previous work, the investigation focuses on step height measurements and lattice parameter evaluation across multiple scan areas. STM images captured in constant-current mode revealed clear atomic terraces and hexagonal lattice patterns, with step heights measured at approximately 332.2–333.9 pm, closely matching the theoretical monolayer thickness of graphite. Interatomic distances between nearest neighbors (140 pm) and atomic rows (245–248 pm) were also consistent with known lattice parameters. In constant-height mode, tunneling current profiles were recorded along line scans of 1.25 nm and 20.7 nm. These profiles exhibited periodic current modulations corresponding to atomic corrugation, with amplitude variations of approximately 0.2 nA. The data confirm the STM’s capacity to resolve both vertical and lateral atomic features with high precision. The study demonstrates the effectiveness of combining imaging modes to extract complementary structural and electronic information from layered crystalline surfaces. The results contribute a validated reference framework for STM calibration and underscore the technique’s reliability in distinguishing atomic-scale topography and local electronic contrast.