Transient absorption spectroscopy with attosecond EUV pulses on binary and ternary solar cell semiconductor systems for the investigations of their charge carrier dynamics

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Semiconductor systems are very important materials today, since their physical properties allow a wide range of applications such as light emitting in diodes, light detectors, optical modulators, high speed electronics or solar cell devices. The knowledge of the underlying electronic processes is the prerequisite for their continuous further development. For decades time-resolved spectroscopy aims for the access to those processes. Investigations revealed the timescales where the slowest processes occur on the picosecond and the fastest on the attosecond timescale. Attosecond transient absorption spectroscopy has emerged from the young field of attosecond science representing today a very powerful tool to study even the fastest processes in matter utilizing single isolated attosecond pulses. This measurement technique revealed the first time-resolved experimental proof of attosecond electron-electron scattering processes in the conduction band of the most common semiconductor material, silicon. The way from primary (Si, Ge) via binary (GaAs) to ternary (AlGaAs) semiconductor systems allowed to increase the efficiency of solar cell devices, since a more accurate tuning to the solar spectrum can be managed. The research project investigates the carrier dynamics in binary and ternary semiconductor systems utilizing attosecond transient absorption spectroscopy to gain access to their fundamental processes. The far-reaching investigation and the knowledge about fundamental charge carrier dynamics, for example charge separation and charge migration, may contribute to improved layer structures or designs and ultimately an increase the efficiency of solar cells. As a consequence the planned research project can, through the application of an attosecond measurement technique to very important semiconductor systems, offer new fundamental physics of solar cells and contribute enormously to the very important field of renewable energies.