Structural investigation of InSe layered semiconductors

During the last decade, III-VI layered semiconductors (GaSe, InSe, GaS, etc.) have emerged as potential candidates for various applications, such as FET and optoelectronic devices. The properties of this class of layered materials are strongly dependent on their structure, and the existence of different polytypes makes it necessary the identification of the structural phase. In this work, we have performed a detailed investigation of the crystal structure and morphology of bulk InSe, by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The combination of the employed techniques allowed to identify the structural phase of InSe samples (epsilon polytype). Most importantly, we show that only by crossing the information of each technique it is possible to unambiguously discern between similar polytypes.