Second harmonic generation for semiconductor materials and interfaces characterization

Wednesday, May 25, 2022 at 1pm
 

In applications such as image sensors or solar cells, the performance of the device can be improved thanks to the passivation of the silicon substrate using high-k dielectrics such as alumina, hafnium dioxide etc. To assess the quality of the dielectric-semiconductor interface, conventional electrical characterization techniques can be employed, but they require fabrication of dedicated test devices. In this project, we develop an innovative characterization method based on a non-linear optics phenomenon, which is the second-harmonic generation (SHG). The particularity of the SHG generated by centrosymmetric materials (such as Si, Al2O3, HfO2…) is that the signal, mainly coming from interfaces contributions, is extremely sensitive to the electrical field (EDC) present there. The electric field at the interface between a dielectric and a semiconductor is related to fixed charges (Qox) and/or interface states (Dit), hence the SHG signal can provide access to these two parameters. In the presentation, I’ll show our latest experimental and simulation results of SHG on passivation layers.