Low-resistance GaN tunnel homojunctions with 150 kA/cm^2 current and   repeatable negative differential resistance
  We report GaN n++/p++ interband tunnel junctions with repeatable negative differential resistance and low resistance. Reverse and forward tunneling current densities were observed to increase as Si and Mg doping concentrations were increased. Hysteresis-free, bidirectional negative differential resistance was observed at room temperature from these junctions at a forward voltage of ~1.6-2 V. Thermionic PN junctions with tunnel contact to the p-layer exhibited forward current density of 150 kA/cm^2 at 7.6 V, with a low series device resistance of 1 x 10^-5 ohm.cm^2. 
Fatih Akyol, Sriram Krishnamoorthy, Yuewei Zhang, Jared M. Johnson,   Jinwoo Hwang, Siddharth Rajan
cond-mat.mtrl-sci cond-mat.mes-hall