Ultrafast Spectroscopy of Semiconductors: A Review on Experimental Methods

Abstract

The advancement of picosecond and femtosecond pulsed lasers made optical spectroscopy a more powerful tool that has been used in the fields of physics, chemistry, and biology. This method is mainly used to study the dynamical properties of various substances such as metals, semiconductors, and superconductors. Ultrafast non-equilibrium carrier excitation of the semiconductor and subsequent relaxation processes occurring on different time scales have become an important area of ​​semiconductor research.   Numerous experimental approaches have been employed to explore these dynamic processes in both semiconductors and their nanostructured counterparts. In this article, we have discussed dynamic phenomena that occur in optically excited semiconductors on time scales from a few hundred femtoseconds to nanoseconds. Among the most widely employed experimental techniques is the ultrafast pump-probe technique, which facilitates the exploration of dynamic phenomena in semiconductors.  This article provides a comprehensive explanation of the basic principles that form the basis of the ultrafast pump-probe technique. Additionally, it highlights significant experimental discoveries obtained through the investigation of semiconductor quantum wells and quantum dots.