@phdthesis{Kayser2021, author = {Kayser, Stefan}, title = {The lateral photovoltage scanning method to probe spatial inhomogeneities in semiconductors: a joined numerical and experimental investigation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-54359}, school = {BTU Cottbus - Senftenberg}, year = {2021}, abstract = {The Lateral-Photovoltage-Scanning-Method (LPS) operates well for Si, Ge and Si_{1-x}-Ge_x for an analysis in defect regions below one part per million, where Secondary Ion Mass Spectroscopy (SIMS) or X-Ray Fluorescence (XRF) signals fall below its detection limit. Although LPS is well established since 1999, it is still poorly investigated. We used a computational simulation finite volume (FVM) approach, solving the van-Roosbroeck equations in three dimensions using a MUltifrontal Massively Parallel sparse direct Solver MUMPS. The signal transport is simulated by solving the Maxwell equations in two dimension for different sample geometries. It could be shown that a typical LPS-measurement is distorted due to the samples geometry (except cuboid). This distortion can be simulated, understood and recalculated, as discussed for trapezoidal or cylindrical samples. Also using the signal generation simulation of this measurement technique it can be shown, that the measurement signal is convoluted depending on the inherent minority charge carrier life time reducing the local resolution. An investigation of the local resolution were made using a Gaussian function as the convolution function of this method. A comparison of simulations to real measurements was discussed on silicon samples with boron implantation pattern. In 1955 Tauc already stated that the bulk photovoltaic effect, causative for the LPS measurement set-up, could be used detecting any quantity, which affects the band structure of a semiconductor.As strain is coupled to the conduction and valence band profiles by the deformation potential theory by van-de-Walle, we investigated the possibility to detect strain variations using LPS simulations. For an n-type Si sample with an on-top stressor stripe (silicon-nitride) the strain distribution in Si got calculated by finite elemente simulation (FEM) using solid mechanics module. By directly converting the strain profile to a single conduction and valence band, FVM LPS simulations were performed. It could be shown, that the LPS voltage can be connected to hole traps caused by the conduction and valence band profile. Therefore we can finally conclude, that the LPS measurement set-up is suitable measuring conduction and valence band variations caused by strain.}, subject = {Silicon; Finite-volume simulation; Lateral photovoltage scanning; van Roosbroeck system; Deformation potential theory; Silicium; Finite Volumen Simulation; Lateral Photovoltage Scanning; Deformationspotential Theorie; Deformationstheorie; Finite-Volumen-Methode; Computersimulation; Laserscanner; Silicium}, language = {en} }