Missions

Energy management is one of the most important challenges facing our society in the 21st century. It is precisely this challenge that is the focus of the research activities of the proposed project, which aims to optimize energy management in a number of markets. In this context, the design of new power switches to manage this energy is essential: losses must be minimized and electrical energy management improved by enhancing the intrinsic characteristics of semiconductor components. Wide bandgap semiconductor materials such as GaN are the ideal candidates to meet this new challenge. The work concerns new manufacturing processes for high electron mobility transistor (HEMT) architectures in gallium nitride (GaN) with “normally-off” functionality. The current major drawback of conventional HEMTs is that they block at negative voltages; this is known as a normally-on component: these conventional HEMT switches are conductive even when the control voltage (gate voltage) is zero.
Several GaN HEMT structures have been proposed in the literature to satisfy the normally-off functionality. In this project, we therefore propose, as a first step, to design normally-off GaN HEMT power devices based on a new 3D approach that should avoid degrading the two-dimensional gas and thus preserve the performance of these devices. Then, in a second step, we propose to design, fabricate, and characterize a switching cell based on these new normally-off GaN switches, which will be monolithically integrated on the same silicon chip.

Activities

The planned work consists of three main phases: 1) Finite element physical simulations to define the best GaN HEMT structure likely to exhibit the desired normally-off functionality, followed by optimization of the geometric and technological parameters of the chosen structure. 2) Technological realization of the structure in the LAAS-CNRS technology platform with the help of GaN wafer suppliers (CRHEA-CNRS, a privileged partner of LAAS-CNRS for 10 years in this field). 3) Technological implementation of a switching cell based on these new normally-off GaN HEMT switches, which will be monolithically integrated on the same silicon chip.

Skills

The skills required for this position are as follows: 1) Solid knowledge of semiconductor physics; 2) Proficiency in finite element simulation software for semiconductor devices (SYNOPSYS-SENTAURUS and/or SILVACO); 3) Extensive experience in microelectronics technology processes (clean room).

Work Context

The work will be carried out at the Laboratory for Analysis and Architecture of Systems (LAAS-CNRS), founded in 1968 and located in Toulouse, Occitanie Region. LAAS-CNRS is a CNRS unit attached to the Institute of Engineering and Systems Sciences (INSIS) and the Institute of Information Sciences and their Interactions (INS2I). The research conducted at LAAS-CNRS aims to provide a fundamental understanding of complex systems while considering their potential applications. More specifically, the work will be carried out within the “Energy Management Systems Integration” (ISGE) team, an internationally recognized research team in the field of power components and integrated circuits (participation in high-level conferences in the field of power engineering as well as in the selection and organizing committees of these conferences, collaboration with European and American manufacturers, , etc.).

Constraints and risks

Part of the work will be carried out at the LAAS-CNRS technology platform, which is part of the national network of seven Renatech RTB (basic technological research) platforms and heads up the GSO-Tech network of technology platforms in southwestern France. Since April 2007, it has benefited from a 1,500 m² clean room with class 10,000 and 100 certification.