Invited
The many expression anharmonic lattice displacements in semiconductors

The dielectric response, charge carrier mobility and lifetimes, and many other physical properties of semiconductors are typically modeled and analyzed in terms of the harmonic motion of the relevant nuclei. While this approach captures the main physical properties of tetrahedrally bonded semiconductors such as silicon and GaAs, we find that the harmonic approximation fails for semiconductors that have more complex structural dynamics.

I will present experimental studies on two types of such semiconductors: halide perovskites and organic crystals. Both types exhibit strong anharmonic displacements, but their anharmonic nature is expressed differently. I will discuss the sources of anharmonicity in these semiconductors, how it affects their dielectric response, charge carrier mobility, lifetimes and defects.