New in-situ optical probing method with an atomic scale resolution for thin film deposition: surface photo-interference (SPI)

A new in-situ optical probing method with an atomic-scale resolution in thin film deposition and/or heteroepitaxial growth is proposed in this paper. The new method is named surface photo-interference (SPI) because it is essentially concerned with a photo-interference in the deposited layer. The principle of the SPI is as follows; the complex refractive indices of the atomic or molecular layers, which alternately appear on top of the surface during film deposition and/or heteroepitaxy, greatly affect the total phase-shift of probing light during propagation in the epilayer, resulting in the change in the photo-interference signal intensity. The experimental setup of the method is very similar to that for another optical probing method called surface photo-absorption (SPA), but the principle is quite different between those two. One of the features of the SPI is that the experimental setup is quite simple and inexpensive though it is quite useful in real time monitoring of the thin film deposition.