Technology transfer to the Ferdinand Braun Institute Berlin was contracted within the 7FP project HipoSwitch. As a part of European consortia, research group led by Dr. Kuzmik at the Institute of Electrical Engineering Slovak Academy of Sciences, developed a new type of AlGaN/GaN transistors. These devices are envisaged in e.g. high-power and effective converters of electric and hybrid cars. It was necessary to propose a technology which could guarantee sufficiently high values of the transistor switching threshold voltage, as well as sufficiently low on-state resistance, and analyze mechanisms of electrical breakdown in off-state. Our proposed technology of manipulating the transistor threshold voltage is based on semiconductor surface plasma oxidation and subsequent oxide deposition in atomic layers. Using this method we have reached the threshold voltage as high as 1.6 V simultaneously with a current density 0.5 A/mm. Analysis of the off-state breakdown pointed on avalanche mechanism coupled with degrading of interfaces. Apart from scientific papers, our results were represented by industrial samples delivered to our partners.
Gregušová, D., Jurkovič, M., Haščík, Š., Blaho, M., Seifertová, A., Fedor, J., Ťapajna, M., Fröhlich, K., Vogrinčič, J., Liday, J., Derluyn, J., Germain, M., and Kuzmík, J.: Adjustment of threshold voltage in AlN/AlGaN/GaN high-electron mobility transistors by plasma oxidation and Al2O3 atomic layer deposition overgrowth, Applied Phys. Lett. 104 (2014) 013506.
Kuzmík, J., Jurkovič, M., Gregušová, D., Ťapajna, M., Brunner, F., Cho, E.M., Menghesso, G., and Wuerfl, J.: Degradation of AlGaN/GaN high-electron mobility transistors in the current-controlled off-state breakdown, J. Applied Phys. 115 (2014) 164504.