Alternative approach for determination of energy band gap of semiconductors through electrical analysis

Abstract

Traditional way of extracting energy band gap (EG) of semiconductors from UV-Visible transmisson measurement becomes difficult once EG lies below than 1 eV. Instead of optical excitation of electrons from valance to conduction bands, Schockley-Read-Hall statistics was considered to determine EG by electrical analysis. According to the statistics, generation recombination and diffusion mechanisms were expected, differing through activation energy. The first processes become dominant at intermatiate temperature where activation energy would be half of the band gap whereas the second one occurs under high temperature side where activation energy would be equal to the band gap. Based on that ac conductance(capacitance)-temperature- frequency (G(C)-T-?) measurements were performed to obtain energy band gap of semiconductors having narrow EG such as iron silicide, ?-FeSi2, chromium silicide, CrSi2 grown on crystaline silicon substrates. Satisfactory EG results were obtained as 0.85 eV and 0.25 eV for ?-FeSi2 and CrSi2, respectively. At last, the approach was tested on well known MIS (abbreviation of metal-insulator-semiconductor) type structure; the acquired EG convinced that the approach was applicable and reliable. © 2009 American Institute of Physics.