Multi-channel tri-gate III-nitride high-electron-mobility transistors

Researchers based in Switzerland and China have fabricated tri-gate metal-oxide-semiconductor high-electron-mobility transistors with five III-nitride semiconductor channel levels, boosting electrostatic control and drive current [Jun Ma et al, Appl. Phys. Lett., vol113, p242102, 2018].

École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland and Enkris Semiconductor Inc in China used a material structure consisting of five parallel layers of a 10nm aluminium gallium nitride (AlGaN) barrier, 1nm AlN spacer and 10nm GaN channel (Figure 1). The barrier was silicon doped at a partial level of 5x1018/cm3 to enhance conductivity. Hall measurements on the five parallel thin two-dimensional electron gas (2DEG) channels gave the sheet resistance as 230Ω/square with 1.5x1013/cm2 carrier density and 1820cm2/V-s mobility (μ). The effective resistivity (ρeff) was 2.4mΩ-cm but with small total thickness (ttot). The team comments: “Small ρeff and high μ are crucial to reduce RON, and a thin ttot facilitates electrostatic gate control and device fabrication (the etching of high-aspect-ratio fins and the formation of electrodes around them can be challenging).”