Thin films of Zr-silicate were deposited on silicon and BK7 glass substrates by EB co-evaporation. The mixing thermodynamics of the ZrO2 - SiO2 system was analysed. Chemical bonding in Zr-silicates has been studied by X-ray photoelectron spectroscopy. The structural and optical properties and the surface morphology were investigated.
The idea of simultaneously using spectroscopic ellipsometry and interferometric microscopy for optical properties
determination of thin absorbing layer is presented. Spectroscopic ellipsometry is a powerful method for thicknesses and
refraction index determination, but in the case of thin absorbing layer a verification method is very useful. Such
verification could be done with interferometric method. With interferometry a phase shift can be observed between two
adjacent areas with different heights and/or optical properties. This phase shift can be accurately calculated with same
model which is used for ellipsometry data analysis.
Proposed method is most effective for metal-insulator-semiconductor structure with thin semitransparent metal
layer. For this structure phase shift and sensitivity to metal thickness and optical indexes can be adjusted by preparing
substrate with suitable dielectric layer thickness.
Method is illustrated with spectroscopic ellipsometry and interferometry measurements on Al-SiO2-Si structure.
In this paper, spectroscopic ellipsometry (SE) has been used to investigate SiO2-Si structures, which were subjected to annealing under a high hydrostatic pressure at high temperature (HPHT) processes. Temperature and pressure varied from 450 degrees Celsius to 1280 degrees Celsius and from 105 Pa to 1.2 GPa, respectively. Investigations have been carried out by variable angle spectroscopic ellipsometer VASE of J.A. Woollam Co Inc. Using the standard optical model of the SiO2-Si structure, no satisfying fit of measured and calculated (Psi) and (Delta) ellipsometric parameters characteristics can be obtained. This inconsistency, expressed by the MSE parameter (Mean Squared Error), is proportional to temperature, pressure and time of the HPHT process. Elongated convexities on SiO2 surface have been observed by scanning electron microscope (SEM). It was found that depolarization effect takes place as a result of non-uniformity of either chemical composition or SiO2 film thickness. A model consisting of upper SiO2 surface roughness, SiO2 layer and SiO2-Si interface has been used for data analysis. Application of this model allowed determination of changes in thickness and refractive index of SiO2 as a result of the HPHT process. An increase of refractive index and decrease of layer thickness can be ascribed to excessive stress in SiO2 layer. This stress has been probably caused by densification of silicon dioxide.
Procedure of chemical preparation of GaSb and particularly wet etching of GaSb surface is still optimized. Properties of surface layers depend on applied etchant. Spectroscopic ellipsometry (SE) is a very sensitive and allows estimation both thickness and layer stechiometry. Best process, which gives thinnest layer, can be determined directly from spectroscopic ellipsometry measurement. Optical properties of surface GaSb oxide often differ from described by Zolner. To determine thickness and refraction index of thin layers optical model of investigated structure is required. By comparing results of calculations for different models best one was found. Layers thicknesses and approximate refraction indices were determined for the surface layers after different etching.
The effects of various chemical treatments on (100) GaSb surface with the aim to develop procedures of polishing of GaSb substrates, surface preparation prior to LPE growth, metal and dielectric deposition, fabrication of patterns have been examined. We show that chemomechanical polishing in Br2 - ethylene glycol followed by anodic oxidation and oxide removal enables to fabricate damage free GaSb surface with the roughness of about 1.5 nm. Surface treatment in 30 HCL-1HNO3 followed by 5%HCL etch gives the best results for surface cleaning prior to metal deposition. The optimum pre-epitaxial treatment includes the use of 1M Na2S solution and H2 anneal. For features patterning 60HCL-1H2O2-1H2O enables etching at rate of approximately 4 micrometers /min, however, to achieve highly anisotropic etching of small size features the use of Ccl4/H2 plasma is the most suitable.
The internal photo injection phenomena in a semitransparent gate metal-oxide-semiconductor (MOS) structure were described among others by the Przewlocki formula. This formula describes the dependence between external voltage applied to the gate to get zero photoelectric current and the light absorption in both electrodes. To study optical properties of the MOS structure, ellipsometric measurements and calculations for the Al-SiO2-Si system were done using J.A. Woolam spectroscopic ellipsometer VASE. The optical model of this structure was determined and used to calculate the dependence of the voltage on the light wavelength (lambda) in Przewlocki's formula.
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