Characterization of Gallium Nitride MOSFET: from lateral to vertical structure.

In a world in which energy efficiency plays an increasingly important role, it is necessary to find valid alternatives to silicon, which can be used in multiple fields, such as automotive, data centers, industrial and aerospace, as well as telecommunications and consumer electronics. Over the last decades, gallium nitride has been widely investigated for the fabrication of power semiconductor devices, since its unique properties can be exploited to obtain efficient and very compact energy conversion systems. In fact, GaN is a wide band-gap semiconductor with an energy gap of 3.4 eV, that enables to design devices able to operate at very high temperatures compared to silicon MOSFETs, which translates in higher power density on the device. Throughout this work, a characterization process will be conducted on both lateral and vertical gallium nitride MOSFETs, to extract relevant quantities as the devices’ threshold voltages and the on-resistance (and their relative drifts due to trapping phenomena) by performing pulsed and transient measurements for different bias conditions at the gate and drain terminals. After each experiment, in order to reset the sample, an Ultraviolet LED having wavelength of 365 nm will be employed to free the carriers from any trap level. Finally, to test reliability and limit performances, a step stress until breakdown will be carried out, every time measuring the current characteristics to state the sample conditions.