Characterization of thin films of Ga 2 Se 3 on Si fabricated using electron beam evaporation technique

Abstract

Many studies have been conducted in the past on compound semiconductor and wide-gap semiconductor for their possible usage in place of oxide in metal-oxide-semiconductor structures for high-speed metal-oxide-semiconductor field-effect transistors application. The best candidates for this purpose, however, are compounds with stoichiometric vacant A 2 III B 3 VI type sites. A 2 III B 3 VI type compounds are wide-gap semiconductors with stoichiometric vacancies and low concentration of free and localized charged carriers. It has that gate insulators can be constructed from wide-gap semiconductor layers with thicknesses smaller than the Debye Screening distance. These new MS'S (metal-Wide bandgap semiconductor-semiconductor) with a good lattice match have less of interface states thus giving better stability to the structure. The idea was to use these MS'S structures for photovoltaic applications with insignificant number of interface states. During literature survey, it was also found that Ga2Se3 is the most prospective candidate for forming a heterostructure with Silicon because of its various properties. Structurally, perfect and homogeneous in thickness Ga2Se3 layers have already been formed in quasi-closed volume by the Hot Wall technique by B. I. Sysoev in the Voronezh Technological Institute, Russia. However, this technology is not cost-efficient for photovoltaic applications, although it has the advantage of better control of Ga and Se components. Over the last few years, many attempts have been made using many other techniques such as Sol-gel technique, vapour phase epitaxy, molecular beam epitaxy, etc. for preparing the thin film of GaSe. The current work is an attempt to prepare the Ga2Se3 film using the electron beam evaporation technique as it appeared to be much simpler. Film of thicknesses varying from 70 to 1000 Å were grown. The films have been studied for their morphology and properties for future use in photovoltaics and other device fabrication like IR detectors, etc. Various techniques were used to study the behavior of the films like XRD, SEM, and TEM.