ABSTRACT
Efficient interband tunneling offers interesting opportunities in a wide bandgap material system such as gallium nitride. An efficient tunnel junction (TJ) can act as a carrier conversion center, converting electrons into holes and vice versa. The standard method of making an interband TJ is to heavily dope the p-type and n-type regions of a PN junction. The high spontaneous and piezoelectric polarization charge along the c-axis of III-nitrides and other highly polar semiconductors provides a new design approach for tunneling structures. For interband tunneling to occur at a very low reverse bias, the indium gallium nitride (InGaN) composition and thickness are chosen such that the polarization-induced band bending aligns the conduction and valence band on either side of the sandwiched InGaN layer. The main enabler for the polarization-assisted TJs is that the polarization field can be aligned to that of the depletion field and band bending required for interband tunneling can be achieved over a small distance.
