Thermoelectricity provides an alternative technological solution to our requirement of power production and refrigeration in eco-friendly manner. Thermoelectric materials with high figure-of-merit are needed to achieve the goal. The book focus that how the semiconductor low-dimensional structures show enhancements in thermoelectric properties. Two alternative methods for identifying worth of semiconducting materials for thermoelectric applications are suggested. The effect of the minority charge carriers and doping amount on material performance at higher temperatures is described and it is obtained that a proper balance between two factors may decide the optimum doping level in semiconductor. The book also describes the spatial confinement effect of acoustic phonons in free-standing quantum wells including the effect on the phonon relaxation rates, electronic transport as well as transport properties of the thermoelement. Author hopes that book will be of interest to those interested in thermoelectric phenomena which is one of the prime clean and green energy options for future.