Study On Thermal Conductivity Of The Nanometer Wurtzite Zinc Oxide Films

Zine oxide film as a wide-bandgap semiconductor naterial with excellent performance,widely concerned in many fields such as photoelectric,piezoelectric,gas sensitive,thermoelectric,ferromagnetic,etc.As the feature sizes of semiconductor devices and MEMS are gradually reduced,the microscale effects of thennal properties are becoming more and more significant.As the core laterial of devices and MEMS,the thermal conductivity of zinc oxide film can directly affect the main perfonnance of devices and systems,it is an important physical parameter related to thennal design and thermal management of devices and systems.Therefore,it is very necessary and practical to carry out research on the thermal conductivity of zinc oxide nano-film materials.Molecular dynamics is an effective way to study the thermal conductivity of nano-films.In this work,the thermal conductivity of zinc oxide nano-films with wurtzite structure was studied by non-equilibrium molecular dynamics method using micro-regular ensemble and Buckingham potential function.The research results show that:(1)The thermal conductivity of a zinc oxide thin film material having a thickness of about 30 to 46 nm at room temperature is two orders of magnitude lower than the thermal conductivity of the bulk material.As the film thickness increases,the thermal conductivity shows a nearly linear increase trend,showing a significant size effect,which is consistent with the trend of experimental test results in the literature.(2)For a zinc oxide film containing oxygen atom vacancies and a film thickness of about 37 nm,the thermal conductivity in the temperature range of 100 to 500K is calculated,it is found that the thermal conductivity of the film decreases with increasing temperature,showing a significant temperature dependence.The simulation results were compared with the test results in the existing literature and the thermal conductivity of bulk zinc oxide.(3)The thermal conductivity of wurtzite zinc oxide nanofilms with oxygen atom vacancy defects is also studied,it is found that the presence of oxygen atom vacancies further reduces the thermal conductivity of the films.For the vacancy-deficient zinc oxide film with a film thickness of about 37 nm,when the oxygen vacancy concentration increases from 0.01085%to 0.05425%,the thermal conductivity decreases from 0.99527 W.m-1·K-1 to 0.86477 W·m-1·K-1 at room temperature.Further,the influence of the temperature on the thermal conductivity of the film having a thickness of 30 nm and an oxygen atom vacancy concentration of 0.0217%was also observed.The phonon aerodynamic theory and the Boltzmann transport equation theory are used to explain the size effect of the film,and the temperature dependence is attributed to the enhanced scattering of phonons by the film boundary.The thermal property data of zinc oxide nanofilms obtained in this paper can provide a certain reference for the thermal design of devices or systems,and also have a positive effect on the preparation and application of oxide film materials.