Thermal Transport In Low Dimensional System

Abstract

The era of semiconductor quantum well commence with the discovery in 1970 by newlineEsaki and Tsu, they invented synthetic superlattices [1] and investigated that any newlineheterostructure that is a combination of superimposing thin layers of semiconductors with newlinedifferent band-gaps results in interesting and advantageous properties [2]. Thence, a lot of newlineefforts and research has been done to investigating the physics in to layered systems to newlinedeveloping the nano devices for vast application in different areas. Physics of newlinesemiconductor layered systems has been a hot topic for the researchers to insight new newlineprospective in industrial use. Development of semiconductor devices using newlinenanostructures made up of multiple semiconductors resulted in Nobel Prizes for Zhores newlineAlferov and Herbert Kroemer in 2000 [3]. From the beginning of the journey of nano newlinestructures, It is the confinement of particles in any particular direction which provide the newlinefoundation stone of the most beautiful assumption of modified phonon dispersion relation newlinein these structures. newlineThere are large number of experimental and theoretical results in the field of newlinelayered systems which bear on the importance of the different type of collisions happens newlineinside the systems. Along this, the anharmonicity is also responsible for many different newlineproperties of the solids and the effects of anharmonicity on scattering events, specifically newlinein layered systems, is relatively unsolved. The defect and phononphonon collision with newlinethe modified dispersion relation in nanoscale systems is a long pending convoluted newlinedilemma which gained interest with the passes of time betwixt the material science newlinephysicists. The impact of confinement, impurities and disarray are well known which newlinedesperately modify the dispersion relation of the systems and may enlighten the physical newlineproperties of these systems in far-reaching context. Further, anharmonicity play an newlinecrucial role in broad angle in the preception of physics of layered systems and their newlineeffects in these systems can not neglects. It is well portrayed that the existence of both newlinedefects and anharmonicities in a crystal governs to the localilized , anharmonic and newline localized-anharmonicity (interference) mode . newlineMost of the features of any crystal can only be explore on the behalf of newlineanharmonic modes in terms of potential energy, that offers the coupling of normal modes newlinein terms of phonon-phonon collision and this makes the study of thermodynamic newlineproperties mandatory as a many body problem. It is remarkable here that the thermal newlineconductivity of system is influenced by confinement, defects, anharminicities, and newlinedispersion relation in a huge manner. The investigation of thermal conductivity in low newlinedimensional systems has been reported either in-plane or total thermal transport inside the newlinelayered systems, but there are no any research which concern about the transport newlinephenomena in the restrain direction. Therefore, we investigate the thermal conductivity of newlinequantum well/superlattice and quantum wire in to in-plane and cross-plane newlinesimultaneously. In the present thesis work, we have taken up the four scattering newlinemechanisms with a different concept considering modified dispersion relation and newlineresolving the thermal conductivity in to in-plane and cross-plane(confined direction). newlineThis thesis work presents a polished theoretical approach to compassionate the elemental newlinephysics of phenomena in low dimensional structur newline