|Location||Call number||Copy number||Status||Date due|
|Sala B : Armadio Tesi||THS_2013 620.5 G791 (Browse shelf)||1||Available|
Thesis for the International PhD in Nanoscience PhD Scuola Superiore di Catania, Catania, Italy 2013 25. cycle.
Includes bibliographical references (p. 148-161).
Today the continuous increase of electric power demand in our society is a global concern. Hence, the reduction of the energy consumption through its efficient use has become the main task of modern power electronics. In this context, wide band semiconductors (WBG), such as silicon carbide (SiC), gallium nitride (GaN) and related alloys, have outstanding physical properties that can enable to overcome the limitations of Silicon, in terms of operating power, frequency and temperature of the devices. An interesting aspect related to GaN materials is the possibility to grow AlGaN/GaN heterostructures, in which a two dimensional electron gas (2DEG) is formed at the heterojunction. Basing on the presence of the 2DEG, AlGaN/GaN heterostructures are particularly interesting for the fabrication of high electron mobility transistors (HEMTs). One of the most challenging aspects in the international GaN devices research community is the development of a reliable way to achieve an enhancement mode HEMT. In fact, enhancement mode AlGaN/GaN HEMTs would offer a simplified circuitry, in combination with favourable operating conditions for device safety. Hence, this thesis is entitled "AlGaN/GaN heterostructures for enhancement mode transistors". The aim of this work was to clarify the mechanisms ruling the electronic transport at some relevant interfaces in AlGaN/GaN devices, after surface modification processes used in normally-off technologies, e.g. plasma treatments or oxidation, deposition of metal contacts or dielectrics, etc. In particular, in this work more emphasis was given to some critical issues related to enhancement mode HEMTs using a p-type doped GaN gate. The use of nanoscale characterization techniques enabled to better link the macroscopic electrical behaviour of these systems with the nanoscale properties of the 2DEG.