Polarization-induced zener tunnel junctions in wide-bandgap heterostructures

The wide bandgap semiconductors such as the lll-V nitrides (GaN, AIN) and SiC, tunneling is low due to the high barrier heights, and is hampered further by the inability to achieve degenerate n and p-type impurity doping. By utilizing the giant built-in electronic polarization fields present in wurzite lll-V nitride semiconductor heterostructures, it is possible to achieve interband tunneling in p-n junction diodes. GaN-AIN-GaN heterostructures were grown by plasma assisted Molecular Beam Epitaxy (MBE) on n-type doped GaN 0001 substrates. The layer structure, and a Transmission Electron Microscope (TEM) image of the GaN/AIN/GaN tunnel junction which was used to confirm the thickness and uniformity of the AIN layer. Current-voltage characteristics of the junctions were measured at 300 K in a probe station using a semiconductor parameter analyzer. By utilizing the polarization fields present in lll-V nitride semiconductors it is possible to generate band to band tunneling. This will enable multicolor light emitters/detectors and multijunction solar cells, as well as enable efficient injection of polarized carriers for spintronic devices.