Optical determination of layered-materials InSe thickness via RGB contrast method and regression analysis.

Indium selenide (InSe) features intriguing thickness-dependent optoelectronic properties, and a simple, and precise way to identify the thickness is essential for the rapid development of InSe research. Here, a red, green, and blue (RGB) color contrast method with regression analysis for quantitative correlation of three optical contrasts from RGB channels with the InSe thickness (1-35 nm), is demonstrated. The lower accuracy of the thickness identification obtained from the individual channels was discussed.