Résumé

AlGaN/GaN HEMTs are very promising candidates for high frequency applications with high power and low noise. Unfortunately, while switching applications strongly demand normally-off operation, conventional HEMTs are normally-on. For the sake of achieving normally-off HEMTs, several structures have been proposed. One of the major normally-off HEMTs uses fluorine implantation in the AlGaN layer. We suggest in this work the implantation of fluorine ions under the AlGaN/GaN interface only below the gate electrode rather than implanting in the AlGaN layer. Simulation results show that the proposed method is capable of achieving normallyoff operation and more effective when it comes to the fluorine concentration required to obtain the desired threshold voltage. Neither the vertical breakdown voltage, nor the off-state current are affectedby this approach.