GaN heterostructure barrier diodes (HBD) with polarization-induced delta-doping

The nonlinear characteristics of solid-state devices are widely used for high frequency applications such as mixers, detectors, and frequency multipliers; for example, the nonlinear rectifying behaviors of Schottky and heterostructure backward diodes are widely used for mixing and detection. Improved flexibility in device design while retaining a rectifying I-V can be realized by back-to-back Schottky diodes, such as by p-type δ-doping in the middle of an intrinsic GaAs layer, known as the Planar Doped Barrier (PDB) diode (Figure 1) [1]. The barrier height and depletion region thickness L1 and L₂ are decided by the position and concentration of the δ-doping (Figure 1 (d)). A reliable PDB is limited by the control of δ-doping. In III-Nitride heterostructures, due to the presence of a high spontaneous and piezoelectric polarization charge, a effective δ-doping can be induced at sharp heterojunctions with atomic control and doping densities far beyond what is achievable by chemical acceptor (or donor) δ-doping in other III-V semiconductors. Polarization-induced sheet charges have not yet been exploited for HBD design in the III-Nitride system; this work presents preliminary results in that direction.