MODELLING AND DESIGN OF DIAMOND POWER SEMICONDUCTOR DEVICES
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With its remarkable electro-thermal properties such as the highest known thermal conductivity (~22 W/cm∙ K at room temperature) of any material, high hole mobility (>2000 cm2/V∙s), high critical electric field (>10 MV/cm), and large bandgap (5.47 eV), Diamond has overwhelming advantages over Silicon and wide bandgap semiconductors (WBG) for ultra-high voltage and high temperature applications (>3 kV and >450 K, respectively). However, despite its tremendous potential, fabricated devices based on this material have not yet delivered the expected high-performance. This is due to three main reasons: (i) the lack of consistent physical models and design approaches specific to diamond-based devices that could significantly accelerate their development; (ii) the absence of shallow acceptor and donor dopant species which has resulted in poor room temperature performance; (iii) the technological issues of the manufacturing process. With the principal aim of modelling the next generation of diamond devices, this Ph.D dissertation endeavours to numerically model the main electro-thermal properties of diamond devices for power electronic applications. Optimized unipolar mode diamond field effect transistors have been designed by means of finite element simulations and their performance has been assessed against the state-of-the-art diamond FETs. Particular attention is given to the static and dynamic properties of deep dopant levels and their effects in WBG semiconductor-based devices. Moreover, by means of a more global comparison technique and through accurate theoretical analysis, diamond FETs and diodes’ performance have been projected and compared with that of GaN and SiC devices. This work concludes with possible implementations of diamond devices in power converters and provides a roadmap of diamond devices for power electronics. These promising results give a new impetus to the rather small, but growing diamond community and enable future research in the field with the goal of bringing diamond to the commercial world.