In recent years CMOS image sensors have gained a major market share for general imaging applications. However, when standard CMOS image sensors are employed in applications that require the detection ...of light with a very small spectral width, like 3D-time-of-flight imaging or other applications with laser light illumination, problems arise, that are negligible in standard imaging applications with broadband illumination. For a given wavelength a strong variation of the sensitivity upon small process related variations of the dielectric stack on top of the photodiodes leads to large die to die variations. In this paper a method is presented that decreases these sensitivity variations by introducing multiple optical path lengths of the dielectric stack within each photodiode. Using this method the maximum quantum efficiency variation for process induced thickness variations could be reduced significantly for a broad range of wavelengths without any additional processing steps.
The clean and hydrogen terminated 2×1-reconstructed Si(1
0
0) surfaces were investigated by surface-core level shift photoelectron diffraction at low kinetic energies. The photoelectron spectra ...contain shifted components due to the different environment of the atoms at the surface. Photoelectron diffraction patterns were recorded for the full solid angle above the sample. The diffraction patterns show different intensity distributions for the different shifted spectral components indicating their local environment. A comparison of experimental and calculated patterns for model structures clearly allows to assign the shifted components to distinct dimer atoms at the Si-surface.
Photoelectron diffraction patterns of the different silicon sub-oxides have been recorded and compared with simulated patterns for various model structures. Each silicon sub-oxide is embedded in an ...ordered environment since individual diffraction patterns and differences among them were exhibited. In particular, the intensity maxima are located at different angles. In the simulation the silicon-oxide/silicon interface was assumed to be abrupt and within one atomic layer. Excellent agreement between experimental and calculated patterns was achieved. At the interface, horizontally compressed SiO
2 was found. Furthermore, the highest oxidation state of silicon, Si
4+, displays a diffraction pattern indicating an ordered structure for this chemical state.
The clean and hydrogen terminated 2x1-reconstructed Si(100) surfaces were investigated by surface-core level shift photoelectron diffraction at low kinetic energies. The photoelectron spectra contain ...shifted components due to the different environment of the atoms at the surface. Photoelectron diffraction patterns were recorded for the full solid angle above the sample. The diffraction patterns show different intensity distributions for the different shifted spectral components indicating their local environment. A comparison of experimental and calculated patterns for model structures clearly allows to assign the shifted components to distinct dimer atoms at the Si-surface.
Angle- and energy-resolved photoelectron diffraction patterns of Si(111) were measured for electron kinetic energies between 196
eV to 784
eV. The diffraction patterns were holographically ...reconstructed in order to obtain real-space atom images of the near-neighbor environment of the emitter. The reconstruction yields real atom positions in a plane parallel to the surface when the spherical electron-wave approximation is used. Also, maxima corresponding to no atom coordinates were found in the reconstruction. Less intense maxima as in the spherical electron-wave approximation were obtained if a complex scattering factor was included in the reconstruction algorithm. The atom images were calculated for different scattering factors used in the reconstruction. These results are compared with the images obtained for a phase-locked summation of the multiple-energy data. This directly demonstrates the sensitivity of the atom images on the phase in a holographic reconstruction from photoelectron diffraction data.
X-ray photoelectron diffraction (XPD) is used as a tool to investigate the growth of Ge on Si(111) with and without surfactant (Sb) mediation. Structural information is extracted directly from the ...forward scattering maxima of recorded photoelectron diffraction patterns. The result of a quantitative analysis of the patterns taken for Ge layers of different coverage are used for a structural growth model of Ge on Si(111). Without Sb, a compression of the top Si and the first Ge double layers is found followed by a relaxation of the Ge structure. Under the presence of Sb an intermixed interface is formed followed by compressed Ge double layers and relaxed distances between double layers.
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