Ammonia-molecular-beam epitaxial growth and optical properties of GaN/AlGaN quantum wells

Abstract

GaN/AlGaN quantum wells on GaN templates have been grown on (0001) sapphire substrates using the ammonia-molecular-beam epitaxy technique. The GaN template layers were of the type used previously for growing high-mobility, heterostructure field-effect transistor structures. The photoluminescence properties of the quantum wells showed strong quantum-confined Stark effect in good agreement with theoretical calculations, as well as evidence of carrier localization due to in-plane well width fluctuation. At low temperature, the quantum well emissions were dominated by two or more localized exciton levels. Carrier thermalization to the lower localized level was observed as the temperature was raised. Evidence of interwell transfer of photocarriers was observed, with the holes appearing to transfer in the direction of the internal field within the AlGaN barrier.

Influence of internal fields on radiative and nonradiative processes in AlN/GaN superlattices

“…The calculated electric fields and ground state emission energies are listed in Table I, along with the observed peak PL energy. 8,10 Given the large PL emission linewidths we observe in our samples, it is unlikely that we would be able to observe with any certainty such small shifts. Figure 2 shows typical photoluminescence spectra recorded at T o Ӎ1.5 K for the three samples, at an excitation power density of 38 kW/cm 2 .…”