Luminescence Spectroscopy of Semiconductors

Abstract

Luminescence of semiconductors is nowadays based on very firm background of solid state physics. The purpose of this book is to introduce the reader to the study of the physical principles underlying inorganic semiconductor luminescence phenomena. It guides the reader starting from the very introductory definitions over luminescence of bulk semiconductors and finishing at the up-to-date luminescence spectroscopy of individual nanocrystals. The book thus set the aim of filling the gap between general textbooks on semiconductors and dedicated advanced monographs. At the beginning, important knowledge of the solid state like lattice vibrations, exciton–phonon interaction and the concept of configurational coordinate are reviewed. Self-contained chapters are then devoted to exciton luminescence processes, effects of high optical excitation, and to an overview of the essentials of electroluminescence. Apart from spontaneous luminescence, special attention is paid to stimulated emission and investigation of optical gain. Considerable space is given also to optical processes in low-dimensional semiconductor structures. The book has been written by experimentalists and is destined primarily for experimentalists, too. Visual approach using schemes and graphs is used frequently instead of rigorous mathematical derivation. The chapter devoted to experimental techniques of luminescence spectroscopy is rich in content. Whenever it makes sense, the accent is put on how to extract from the appearance of luminescence emission spectrum (shapes of emission lines, their behaviour with varying experimental parameters) as much information on microscopic origin of luminescence as possible. The book cannot be regarded as a comprehensive monograph on semiconductor luminescence; selected examples from extremely rich literature only have been chosen to illustrate the text.

Temperature dependence of the band gap of zinc nitride observed in photoluminescence measurements

“…The observed red-shift with increasing temperature follows the well-known Varshni equation, which empirically describes the effect of thermal vibrations on the bandgap of semiconductors. 9,10 Band A also exhibits a highenergy tail, more clearly observed at T ¼ 300 K, which is indicative of transitions that involve the recombination of free carriers 10 and correlates with a high n-type carrier density of $10 19 cm À3 found in these samples through Hall measurements. The high carrier density is thought to originate from native defects in the samples as observed generally in Zn 3 N 2.…”

“…In addition, the overall material quality can be assessed through the photoluminescence yield and its temperature and excitation intensity dependence. 9,10 There have been only a few reports of photoluminescence in Zn 3 N 2 films in the case of both narrow and wide bandgap sample types reported in the literature. 11,12 Furthermore, the temperature dependence of these bands has not been investigated fully, and photoluminescence studies have not to date shed light on the nature and size of the bandgap in Zn 3 N 2 .…”

Photoneutralization and slow capture of carriers in quantum dots probed by resonant excitation spectroscopy

“…Let us now discuss the power dependence introduced for γ 1 and γ 2 . Considering the evolution of the barrier electron (hole) population N e (N h ) under a non-resonant excitation [37] and the fact that the photoluminescence of the GaAs barrier is not influenced by the QDs population [38], the populations N e and N h created by the optical gate are governed by bimolecular interband radiative recombination [13,37] and are proportional to √ P gate . The carriers can be then captured in the QD and the defect in its vicinity, either by the emission of optical phonons, or by Auger processes.…”

Microstructure and Thermally Stimulated Luminescence of β -Ga2O3Thin Films

“…We applied the partially heating method and derived spectroscopy method [11] in order to check experimentally the decomposition performed. Since the low-temperature part of a TSL peak in the case of linear kinetics of luminescence, is of a larger extent as compared to its high-temperature part [12], it has been established that recombination processes at the indicated TSL peaks are described by linear kinetics.…”