Optical investigations of Berthelot-type properties in quaternary AlInGaN multiple quantum well heterosystems

The anomalous Berthelot-type optical properties of quaternary AlInGaN heterostructure with different quantum well pairs have been investigated systematically in this study. A microscopic model based on the luminescence observations of a comparison between an Arrhenius-type radiative process and a Berthelot-type nonradiative process has been proposed to elucidate the temperature dependence of the optical and transport behavior in nanocrystalline and amorphous semiconductors. The photoluminescence of the AlInGaN heterostructures is also found to exhibit unique luminescence features such as S-shaped emission peak energy and W-shaped full-width at half-maximum (FWHM) curves over a broad range of temperature. We investigated in detail the aspects of luminescence that would provide significant information regarding the degree of disorder in AlInGaN-based semiconductor heterosystems, leading to the appearance of the Berthelot-type behavior. The increase of quantum-well pairs apparently will cause the incorporation of indium atoms in the AlInGaN nanostructures, resulting in augmentation of the degree of crystalline randomization. In other words, the higher degree of disorder in AlInGaN heterostructures, the longer the static microbarrier width and the more obvious carrier localization effects may be observed.