Performance Analysis On The Resonant Tunneling Electron Refrigerators In The Nanowire Heterojunction

Electronic refrigeration technology may achieve the cooling through the electron carrying heat in the process of transport. Compared to the traditional refrigeration technology which relies on the liquid, gaseous or chemical changes of the medium, the electron refrigerator has many advantages, such as high efficiency and non-pollution, and so on. The electron refrigerator uses the electrons as the working substance, which consists of two thermal reservoirs with different temperatures and chemical potentials and the energy filter. When the electrons transport from the cold reservoir to the hot reservoir through the energy filter, the heat flux is formed. The electrons will absorb heat from cold reservoir and release it to the hot reservoir. It results in the decrease of the cold reservoir's heat and the increase of the hot reservoir heat, and achieves the purpose of cooling. The transmission probability of the electron between the two thermal reservoirs affects directly the heat flux and the coefficient of performance, while the transmission probability depends on largely the structure of the energy filter. In this thesis, base on the transfer matrix method and the theory of the electron transport, the performance characteristics of the resonant tunneling electron refrigerators in the nanowire heteroj unction is studied. It will provide the theoretical guidance for the design and manufacture of the real electron refrigerators.Firstly, the electron resonant transport through a Lorentz-type energy transmission spectrum between the two reservoirs with different temperatures and chemical potentials is studied in Chapter 2. The heat flux through the electron resonant transport is obtained. After considering the radiant heat leakage between the two reservoirs, the performance parameters of electron heat pump are numerically calculated, and the performance characteristic curves are drawn. The influence of the heat leakage, the position of resonant center energy level and the width of energy level on the performance characteristics of the heat pump is discussed. When the width of the resonance energy is large, the maximum coefficient of performance increases as the width of energy level decreases. When the width of the resonance energy is small, the effect of the heat leakage becomes significant large and the maximum coefficient of performance decreases as the width of energy level decreases.Next, the electron resonant transport through a double-barrier InAs/InP nanowire heterostructure is studied in Chapter 3. Based on the electron transfer matrix method, the transmission probability is obtained. Moreover, the heat flux generated by electronic transport is calculated. The performance characteristic curves of the electron refrigerator are drawn. The influence of the width of potential barrier and well on the performance of refrigerator is analyzed. It is shown that if the well width is given, the position of resonance center level increases and the width of resonance level decreases as the width of potential barrier increases. The cooling rate corresponding to the same bias voltage decreases and the relative coefficient of performance increases. For given the width of the potential barrier, the cooling rate corresponding to the same bias voltage decreases as the width of the well increases. The cooling rate and the relative coefficient of performance are mainly affected by the change of the width of the potential well.Lastly, the performance of the electron refrigerator with a multi-barrier nanowire heterostructure is studied in Chapter 4. The transmission probability is obtained by using the transfer matrix method, the influence of the bias voltage and the heterostructure on the performance of the electron refrigerator is analyzed. Influence of the barrier height and width of the middle barrier on the transmission probability, cooling rate and performance of coefficient is mainly discussed.