Dans le cadre du thème GaN, l’IEMN accueille :
Lundi 27 Mars 2017 – IEMN LCI Villeneuve d’Ascq, Salle du conseil – 10:30
Nanostructured GaN devices for power applications and beyond
Elison Matioli, Ecole Polytechnique Fédérale de Lausanne (EPFL)
In this talk, I will present some of the nanowire-based technologies developed in our group to significantly enhance the performance of high-voltage GaN power devices, such as Schottky barrier diodes (SBDs) and high electron mobility transistors (HEMTs). This presentation will cover high-performance AlGaN/GaN HEMTs on silicon substrate based on nanowire tri-gate architectures. The optimized tri-gate geometry led to reduced off-state leakage current (Ioff) and sub-threshold slope (SS), increased on/off ratio, and improved breakdown voltage (Vbr) of the device. With a gate-to-drain separation (LGD) of 15 μm, hard Vbr up to 1755 V at Ioff of 45 μA/mm with high soft Vbr of 1370 V at Ioff = 1 μA/mm were achieved, rendering an excellent high-power figure of merit (FOM) up to 1.25 GW/cm2.
These nanowire-based technologies were also applied for AlGaN/GaN SBDs on silicon substrates. An optimized hybrid of tri-anode and tri-gate architectures led to SBDs exhibiting high Vbr, low reverse leakage current (IR), and small turn-on voltage (VON) of 0.76 ± 0.05 V since the tri-anode architecture formed a direct Schottky contact to the 2D electron gas (2DEG). The reverse characteristics were controlled electrostatically by an embedded tri-gate transistor, instead of relying only on the Schottky barrier, which resulted in low IR below 10 nA/mm at large reverse biases up to 500 V. In addition, these devices exhibited record Vbr up to 1325 V at IR of 1 μA/mm, rendering an excellent high-power FOM of 939 MW/cm2. These results unveil the significant potential of nanostructured GaN transistors for future power applications.
Finally, I will discuss the application of these nanostructures to better understand the electron transport in GaN-based heterostructures, which was exploited to demonstrate new ballistic devices operating at room temperature. The fast transport of ballistic electrons could offer a pathway for future room-temperature high-frequency ballistic devices.
Biography: Elison Matioli is an assistant professor in the institute of electrical engineering at Ecole Polytechnique Fédérale de Lausanne (EPFL). He received a B.Sc. degree in applied physics and applied mathematics from Ecole Polytechnique (Palaiseau, France) in 2006 and a Ph.D. degree from the Materials Department at the University of California, Santa Barbara (UCSB) in 2010. He was a post-doctoral fellow in the Department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology (MIT) until 2014. His expertise is in semiconductor and nanostructure growth by metal-organic chemical vapor deposition (MOCVD), device fabrication and development of advanced numerical models to simulate device properties. He has received the Outstanding Graduate Student – Scientific Achievement Award for his Ph.D. thesis, the IEEE Electron Devices Society George Smith Award for his demonstration of high-efficiency nanostructured power electronic devices and the ERC Starting Grant in 2015.