Phonons in Nanostructures

Abstract

This book focuses on the theory of phonon interactions in nanoscale structures with particular emphasis on modern electronic and optoelectronic devices. The continuing progress in the fabrication of semiconductor nanostructures with lower dimensional features has led to devices with enhanced functionality and even novel devices with new operating principles. The critical role of phonon effects in such semiconductor devices is well known. There is therefore a great need for a greater awareness and understanding of confined phonon effects. A key goal of this book is to describe tractable models of confined phonons and how these are applied to calculations of basic properties and phenomena of semiconductor heterostructures. The level of presentation is appropriate for undergraduate and graduate students in physics and engineering with some background in quantum mechanics and solid state physics or devices. A basic understanding of electromagnetism and classical acoustics is assumed.

Unified treatment of coupled optical and acoustic phonons in piezoelectric cubic materials

“…It is demonstrated in a first unified approach that optical and acoustic phonons are inherently coupled in piezoelectric materials, and we compare with the existing literature in the field where optical and acoustic phonons are treated separately [27][28][29][30][31]. This coupling of optical and acoustic phonons is important for the understanding of electron-phonon interaction selection rules in piezoelectric materials and, e.g., Raman scattering processes.…”

Excited-State Dynamics in Colloidal Semiconductor Nanocrystals

“…The interested reader is referred to a number of publications addressing this topic in detail [36][37][38][39][40][41][42][43][44][45][46][47][48]. Phonons (i.e., lattice vibrations) have a pervasive role in semiconductors, and therefore coupling of charge carriers and excitons to phonons plays a decisive role in a wide range of properties [49]. The interaction between phonons and excitons in nanoscale semiconductors is expected to differ from that in bulk materials due to both quantum confinement effects on the exciton energy levels and dimensional confinement of phonon modes (i.e., the phonon wavelength cannot be larger than the NC size) [49].…”

“…Phonons (i.e., lattice vibrations) have a pervasive role in semiconductors, and therefore coupling of charge carriers and excitons to phonons plays a decisive role in a wide range of properties [49]. The interaction between phonons and excitons in nanoscale semiconductors is expected to differ from that in bulk materials due to both quantum confinement effects on the exciton energy levels and dimensional confinement of phonon modes (i.e., the phonon wavelength cannot be larger than the NC size) [49]. Coupling of photogenerated carriers to phonons provides an important energy relaxation pathway, thus being essential to a number of photophysical processes in semiconductor NCs (e.g., exciton relaxation dynamics, carrier cooling, thermal transport) [42,[50][51][52][53].…”

Khatkevich's theory for acoustic axes in 6mm piezoelectric CdS

“…They have provided a solid basis for modeling phonon behavior in nanoscale materials [2]. An insight into energy transport carried by nonequilibrium phonons has great importance for both designing and optimizing electronic and optical devices for various working medium scale.…”