Lateral redistribution of trapped charges in nitride/oxide/Si (NOS) investigated by electrostatic force microscopy.

Charge decay and lateral spreading properties were characterized by modified electrostatic force microscopy (EFM) under a high vacuum at elevated temperatures. Variations in the charge profiles were modeled with the maximum charge density (ρ(m)) and the lateral spreading distance (Δ(s)), as extracted from the EFM potential line profiles. The scaling limitation of nitride trap memory is discussed based on the projected lateral spreading distances for holes and electrons, which were determined to be approximately 18 nm and 12 nm, respectively, at room temperature.

Simulation of depolarization effect by a rough surface for spectroscopic ellipsometry.

We employed the integral equation method (IEM) to simulate optical scattering by a randomly rough surface for spectroscopic ellipsometry. An explicit Mueller-matrix expression of the IEM for single scattering by moderately small surface roughness makes it possible to calculate the depolarization effect. The IEM allows a relatively rigorous assessment of the surface-scattering effect in a wide spectral range.

Simulation of the depolarization effect in porous silicon.

We describe a radiative transfer (RT) equation for the simulation of optical scattering effects in a nanostructured semiconductor for spectroscopic ellipsometry (SE). As an example, we chose porous silicon (PS), whose pores are considered to act as light scatterers. We examined the effects of pore radius, slab thickness, and incident angle. The volume scattering effect in the internal morphology of the PS generates incoherent light, leading to depolarization. By simulating the four Stokes parameters through the RT equation, we could theoretically assess the degree of polarization that is essential for SE measurements of some nanostructured semiconductors.