Ultralow-voltage-drop GaN/InGaN/GaN tunnel junctions with 12% indium content

We report a combination of highly doped layers and polarization engineering that achieves highly efficient blue-transparent GaN/InGaN/GaN tunnel junctions (In content = 12%). NPN diode structures with a low voltage drop of 4.04 V at 5 kA/cm2 and a differential resistance of 6.51 × 10−5 Ωcm2 at 3 kA/cm2 were obtained. The tunnel junction design with n++-GaN (Si: 5 × 1020 cm−3)/3 nm p++-In0.12Ga0.88N (Mg: 1.5 × 1020 cm−3)/p++-GaN (Mg: 5 × 1020 cm−3) showed the best device performance. Device simulations agree well with the experimentally determined optimal design. The combination of low In composition and high doping can facilitate lower tunneling resistance for blue-transparent light-emitting diodes.