Direct Observation of Pyroelectric Fields in InGaN/GaN and AlGaN/GaN Heterostructures

In this paper we investigate the influence of spontaneous polarization on the luminescence behavior of nitride heterostructures. Spontaneous polarization is normally screened by charged surface adsorbates. Using electron stimulated desorption we can remove this coverage and spontaneous polarization comes into effect. For GaN/Al0.15GaN and In0.11GaN quantum wells this results in an enormous blue-shift of the emission, in our case of up to 500 meV. In bulk-like layers the Franz-Keldysh effect slightly lowers the emission energies and the lines become broadened.