{"content":[{"text":"Wroclaw, 11.12.2020","bbox":{"left":0.706184,"top":0.082217,"width":0.17417899999999997,"height":0.019196000000000005}},{"text":"PhD dissertation abstract","bbox":{"left":0.381516,"top":0.116087,"width":0.23596699999999998,"height":0.022396}},{"text":"Investigations of thermal conductivity of nitride semiconductors \n thin films","bbox":{"left":0.132423,"top":0.153876,"width":0.7342200000000001,"height":0.059275999999999995}},{"text":"Alexandra Filatova-Zalewska","bbox":{"left":0.359751,"top":0.229383,"width":0.28009,"height":0.02239599999999997}},{"text":"During the last fifty years from the moment, when the first GaN-based light-emitting diode was \n presented, interest in fabrication and application of nitride devices systematically grew up. \n Today, GaN and GaN-based materials, such as AlGaN or InGaN, are used as ultraviolet \n detectors, laser diodes, high-electron mobility transistors and can potentially be used as \n thermoelectric materials. Self-heating is a serious problem in the case of high electron mobility \n transistors - it leads to decrease of their efficiency. If one wants to increase performance of \n those devices, it is necessary to use material with high thermal conductivity. On the other hand, \n good thermoelectric material has high electrical conductivity, high Seebeck coefficient and low \n thermal conductivity. One can see, it is important to define thermal conductivity of the material, \n used in the device.","bbox":{"left":0.118235,"top":0.301969,"width":0.765135,"height":0.24065799999999998}},{"text":"Up to this day, thermal conductivity of bulk and film GaN was extensively investigated, while \n rather small amount of works was dedicated to determination of thermal conductivity of films \n and superlattices of GaN-based alloys. The objective of this thesis was the investigation of \n thermal conductivity of AlGaN films and AlGaN/GaN superlattices and explanation of heat \n transfer mechanisms in those materials.","bbox":{"left":0.118518,"top":0.557206,"width":0.764679,"height":0.117529}},{"text":"For implementation of this task experimental setup for thermal conductivity measurement with \n the use of 3co method was constructed. On this setup isotropic thermal conductivity of AlGaN \n films and anisotropic thermal conductivity of AlGaN/GaN superlattices were measured. For \n description of the obtained experimental results was used Callaway model together with the \n virtual crystal model.","bbox":{"left":0.118981,"top":0.689742,"width":0.7619319999999999,"height":0.11752800000000008}},{"text":"Isotropic thermal conductivity of 500 nm-thick AlxGa1-xN films (x � 0.045, 0.075, 0.102) was \n measured in the temperature range from 150 K to 300 K. Thermal conductivity increased with \n both increasing temperature, and this temperature dependence can be explained with dominance \n of phonon-boundary and phonon-alloying element scattering mechanisms. Also a decrease of","bbox":{"left":0.118467,"top":0.822277,"width":0.765014,"height":0.09273199999999993}},{"text":"1","bbox":{"left":0.873052,"top":0.925942,"width":0.007859999999999978,"height":0.01606799999999997}}],"images_bbox":[],"images_bbox_not_text_overlap":[]}