Control of Resonant Tunneling transport in III-Nitride Double-Barrier Heterostructures by δ-doping engineering*

The spontaneous and piezoelectric polarization fields in III-Nitride semiconductors control their electronic, optical, and piezoelectric properties. Accordingly, the fundamental physics of resonant tunneling transport through nitride resonant tunneling diodes (RTDs) is also dominated by the built-in polarization fields. We have recently elucidated this connection by developing a transport model which reproduces the measured tunneling currents in multiple RTD designs. Using this model and the exponential dependence of the currents on the electric fields, we measured the polarization fields with unprecedented precision.

III-Nitride RTDs are also of interest in practical applications since they provide electronic and optical gain within the THz band. However, because of the internal fields, the resonant levels shift toward higher energies due to the electrostatic polarization of the barriers and quantum-confined Stark effect in the well. Thus, the resonant voltages exhibit values > 4 V, for multiple RTD designs. Here, we present a new δ-doped GaN/AlN RTD which enables control over the resonant voltages, making them independent of the built-in fields. We demonstrate devices with resonant voltages ~1 V, while maintaining a high current density and peak-to-valley current ratio.