From projected phase to surface-state electrostatics in FIB-prepared semiconductor lamellae

Abstract Off-axis electron holography provides quantitative access to projected electrostatic potentials in semiconductor devices. However, focused-ion-beam (FIB) preparation can substantially modify the near-surface electrostatics of transmission electron microscopy lamellae. These effects redistribute the internal potential through surface-state charging, band bending, and screening, making the measured phase difficult to interpret in terms of the crystalline device core. Here, we establish a physical interpretation of the multilayer Simple and Intuitive Model for Potentials (SIMP), a three-dimensional forward-modeling framework for reconstructing electrostatic potentials from projected electron-holographic phase images, by relating its phenomenological parameters to effective screening lengths, near-surface band bending, electric fields, and charge carrier densities. As an illustration, the framework is then applied to symmetrically doped Si p-n junction lamellae prepared at final FIB acceleration voltages of 2 kV and 30 kV. The results show that reduced projected fields can arise primarily from averaging over preparation-modified near-surface regions rather than from intrinsically weak junction electrostatics. This advances multilayer SIMP from an empirical reconstruction method towards a physically anchored framework for quantitative electrostatic characterization of FIB-prepared semiconductor nanostructures.