Thermodynamic photoinduced disorder in AlGaN nanowires

Abstract

In this study, we examine thermodynamic photoinduced disorder in AlGaN nanowires through their steady-state and transient photoluminescence properties. We correlate the energy exchange during the photoexcitation and photoemission processes of the light–solid reaction and the generation of photoinduced entropy of the nanowires using temperature-dependent (6 K to 290 K) photoluminescence. We observed an oscillatory trend in the generated entropy of the system below 200 K, with an oscillation frequency that was significantly lower than what we have previously observed in InGaN/GaN nanowires. In contrast to the sharp increase in generated entropy at temperatures close to room temperature in InGaN/GaN nanowires, an insignificant increase was observed in AlGaN nanowires, indicating lower degrees of disorder-induced uncertainty in the wider bandgap semiconductor. We conjecture that the enhanced atomic ordering in AlGaN caused lower degrees of disorder-induced uncertainty related to the energy of states involved in thermionic transitions; in keeping with this conjecture, we observed lower oscillation frequency below 200 K and a stable behavior in the generated entropy at temperatures close to room temperature.