Characterizing optical and geometrical properties of semiconductor thin films with a split-step angular spectrum approach to inverse synthesis

As semiconductors are critical for the development of photonic technologies, they must have their optical properties measured precisely to be incorporated into respective devices. A promising method for measuring these optical properties is thin film transmission spectroscopy, which obtains the complex refractive index of a semiconductor over a wide wave band by analyzing the transmittance spectrum of the semiconductor with computational algorithms. Recently, our team has introduced a novel method that can characterize many “geometrical properties” of a thin film system, like the film surface shape, in addition to the optical properties. Similar to related techniques, our method relies on global optimizers, which introduces variance to the optical property measurements. In this contribution, we test multiple global optimizers for this analysis, and evaluate best global optimizer that both precisely measures data and minimizes measurement variance of our method.