Inversion of the internal electric field using delta doping in Al0.3Ga0.7N/GaN heterostructures

Controlling the internal electric field in III-nitride heterostructures is essential for optimizing device performance. These fields, arising from polarization effects, impact carrier confinement, wavefunction overlap, and band structure. In LEDs and lasers, reducing the field mitigates the quantum-confined Stark effect, enhancing efficiency. This study explores n-type delta doping in AlN/GaN and Al0.3Ga0.7N/GaN heterostructures to engineer and even invert locally the internal electric field. Simulations predict that inversion should be possible for Al0.3Ga0.7N layers inserting a delta doping concentration above 1.4 × 1013 cm−2. Off-axis electron holography experiments have been used to measure the electrostatic potential and have confirmed the electric field inversion obtained through Si delta doping. On the contrary, Ge doped layers did not show any inversion of the electric field due to Ge migration. Therefore, Si is more suitable for donor electric field engineering via delta doping.