Atomic force microscope for direct comparison measurement of step height and crystalline lattice spacing

A new atomic force microscope (AFM) for direct comparison measurements of step heights and crystalline lattice spacing has been developed. The AFM is equipped with a cantilever with a lead zirconate titanate (PZT) thin film sensor, a reference crystal technique with a scanning tunnelling microscope (STM) for step height measurement, high accuracy mechanisms, and an interferometer. A mono-atomic step on a surface of sapphire (0001) has been measured to show the performance of the AFM. The measured step height of the mono-atomic step calibrated by the interferometer in real time was 0.21±0.07 nm (1σ) and from the known lattice constant of graphite of 0.246 nm, a step height of 0.19±0.05 nm (1σ) can be derived for the sapphire sample, both of which agree with the known value of a single step of 0.22 nm.