Piezoelectric Stark-like Ladder in GaN/GaInN/GaN Heterostructures

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Abstract
The electronic bandstructure of strained Ga1-x InxN wells between barriers of GaN is found to exhibit an unusual Stark-ladder controlled mainly by the piezoelectric dipole across the strained layer. In luminescence and reflection spectroscopy four distinct steps including a strong redshift with respect to the thin film band gap are identified. Huge piezoelectric fields F ≤1 MV/cm are derived directly from Franz-Keldysh oscillations and interband transitions between carriers originating on opposite sides of the well. For the largest strain and electric field, a Stark-like ladder is identified. This provides important details for the interpretation of the electronic band structure in group-III nitride heterostructures.