GaN-Based Transistors with Trigate Architecture

• Applicants: Professor Dr. Oliver Ambacher; Privatdozent Dr.-Ing. Frank Schwierz
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 243486436

GaN HEMTs (High Electron Mobility Transistor) have become popular devices recently, in particular for application in power switches and RF (Radio Frequency) power amplifiers. Power switches and RF amplifiers are key components for modern information and communication technology. The application of GaN transistors in these components offers many advantages and therefore the development of GaN transistors, in particular GaN HEMTs, is pushed forward aggressively. Most GaN HEMTs realized so far are dHEMTs (depletion HEMT) having a conducting channel at zero applied gate voltage. This seriously limits their potential application areas since frequently eHEMTs (enhancement HEMT) are needed that for zero gate voltage are switched off. The present project is focused on a new and promising transistor architecture, namely the trigate concept that became popular in silicon electronics quite recently. In the project, this concept will be adopted to GaN HEMTs and in-depth research on GaN trigate eHEMTs will be carried out. The three project partners with recognized expertise in transistor theory and GaN technology will conduct research on GaN trigate structures with special emphasis on GaN trigate eHEMTs for power switches and RF amplifiers. They will closely collaborate and - investigate the physics and operation of GaN trigate eHEMTs in detail,- elaborate suitable designs of such transistors for power switches and RF applications,- develop and establish a complete process flow for GaN trigate HEMTs, - fabricate GaN trigate eHEMTs and perform a thorough electrical characterization of these transistors,- assess the potential of the trigate concept for GaN.Extensive device simulations will be performed to get insights in the physics and operation of GaN trigate HEMTs. The obtained results serve as basis for elaborating suitable designs of trigate eHEMTs for power switches and RF applications. From the processing point of view, major challenges are the fabrication of the AlGaN/GaN bodies for trigate HEMTs by etching deep trenches, thereby avoiding the formation of defects at the body sidewalls, and the deposition of metals and dielectrics on the sidewalls. Key targets of the project are (i) the realization of GaN trigate eHEMTs that successfully compete with conventional GaN top-gate HEMTs, (ii) a significant enhancement of the state of knowledge on GaN trigate HEMTs, and (iii) a well-founded and critical assessment of the potential of these transistors.

• DFG Programme: Research Grants