C.W. van Hasselt

Electric field induced second harmonic generation spectroscopy on a metal‐oxide‐silicon structure

Spectroscopic electric‐field‐induced second harmonic generation on a Si(111)–SiO2–Cr metal‐oxide‐silicon structure shows a bias‐independent ‘‘interface’’ resonance at 3.25 eV and a ‘‘bulk’’ resonance at 3.43 eV which is strongly bias dependent. The symmetry forbidden bulk dipole contribution becomes observable, and even dominating, due to the bias‐induced band‐bending that breaks the bulk inversion symmetry. The origin of these resonances is discussed, as well as the prospects for using second harmonic generation as a probe of metal‐oxide‐silicon characteristics.

Second-harmonic generation from thick thermal oxides on Si(111): the influence of multiple reflections

Recently a number of second-harmonic-generation (SHG) experiments on (thick) oxide films on Si were performed as studies of the possible presence of strain, crystalline SiO2, a static electric field, and roughness at the Si–SiO2 interface. Large enhancements of the SHG anisotropy have been observed for thick oxide films. We show here that the SHG for thick thermal oxide films on Si(111) as a function of oxide thickness and angle of incidence is dominated by linear optics, owing to multiple reflections in the oxide film.

Optical second-harmonic generation studies of thin lead-zirconate-titanate ferroelectric films

Abstract Optical second-harmonic generation was used to study the microscopic structure of thin PZT films for various Pb concentrations. From the polarization and angular dependence of the nonlinear response, information about the distribution of microcrystallites can be obtained.

Second Harmonic Generation and Atomic-Force Microscopy Studies of Porous Silicon

Structural properties of porous silicon were studied with atomic‐force microscopy (AFM) and optical second harmonic generation (SHG). Depending on etching conditions, the SHG response was observed to be either anisotropic, showing C2v symmetry, or isotropic. This correlated with AFM observations of quasi ordered structures in the first case. The Si etching process was studied by in situ SHG measurements.

Oxide-thickness dependence of second harmonic generation from thick thermal oxides on Si(111)

We show here that the oxide-thickness dependence of the s-polarized SHG from Si(111) covered with a thick thermal oxide is completely described by multiple reflections in the oxide film. For the p-polarized response, a strong enhancement with thickness is observed, which cannot be explained in this way. These measurements show that one should be cautious in analyzing the SHG from a buried interface, and carefully take into account the linear optics involved.

Effect of Linear Polarisability and Local-Fields on Surface Shg

A discrete dipole model has been developed to describe Surface Second Harmonic Generation by centrosymmetric semiconductors. The double cell method, which enables the linear reflection problem to be solved numerically for semi-infinite systems, has been extended for the nonlinear case. It is shown that a single layer of nonlinear electric dipoles at the surface and nonlocal effects allows to describe the angle of incidence dependent anisotropic SHG obtained from oxidised Si(001) wafers. The influence of the linear response, turns out to be essential to understand the anisotropic SHG-process.

Probing the silicon-silicon oxide interface of Si(111)-SiO2-Cr MOS structures by DC-electric-field-induced second harmonic generation

The buried Si(111)-SiO 2 interface has been studied in transmission through planar Si-SiO 2 -CS MOS structures using DC-electric-field-induced second-harmonic generation (EISHG). The rotational anisotropy and oxide thickness dependence of EISHG have been measured. Multiple reflections in the oxide layer and interference effects between field-dependent and field-independent contributions to the nonlinear polarization are shown to affect the shape of the EISHG bias dependence. From a simple model the relative size of field-dependent and field-independent contributions can be estimated. In this way, information about the interface charge distribution can be obtained.

In situ characterization of SiO2 etching with second harmonic generation and ellipsometry

Abstract The etching process of SiO 2 films on Si(111) was studied by in situ second harmonic generation (SHG), linear reflectivity and ellipsometry. All measurements are very well described with one simple model, with only the etching speed as adjustable parameter. In contrast to the linear optical measurements SHG shows high interface sensitivity when the silicon is etched clean.

Second harmonic generation from thick thermal oxides on Si[111]: the influence of multiple reflections

Recently a number of second-harmonic-generation (SHG) experiments on (thick) oxide films on Si were performed as studies of the possible presence of strain, crystalline Si0 2 , a static electric field, and roughness at the S i-S i0 2 interface. Large enhancements of the SHG anisotropy have been observed for thick oxide films. We show here that the SHG for thick thermal oxide films on S i ( ll l) as a function of oxide thickness and angle of incidence is dominated by linear optics, owing to multiple reflections in the oxide film.