Large enhancement of interband tunneling current densities of over 10/sup 5/ A/cm/sup 2/ in In/sub 0.53/Ga/sub 0.47/As-based surface tunnel transistors

In/sub 0.53/Ga/sub 0.47/As-based Surface Tunnel Transistors (STT's), which control an interband tunneling current between an n-type channel and a p-type drain by an insulated gate, are investigated with the goal of increasing the tunneling current-density for high-speed operation. The fabricated devices enhanced an interband tunneling current density by a factor of 102compared to the conventional GaAs-STT's due to a smaller bandgap energy and a lighter electron effective mass, and exhibited a clear gate-controlled negative differential resistance (NDR) characteristics with maximum tunneling current densities of over 105A/cm2. The cutoff frequency (FT) and maximum oscillation frequency (fmax) of a fabricated device with a 1.0-μm gate length were estimated to be 7.9 GHz and 20 GHz, respectively, in the NDR region.