Growth and properties of nonperiodic multiple thin films

• Published in: Thin solid films Vol. 306; no. 2; pp. 346 - 351
• Main Author: Sasaki, Akio
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 11.09.1997
• Subjects: Luminescence of superlattices; MBE of AlGaAs and SiGe heterostructures; Nonperiodic multiple thin films; Nonperiodic multiple thin films; MBE of AlGaAs and SiGe heterostructures; Luminescence of superlattices
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(97)00289-7

Nonperiodic multiple thin films of AlGaAs and SiGe materials are grown by molecular beam epitaxy, and their luminescence properties are investigated. The layer thicknesses of individual films are nonperiodically, i.e., randomly varied along the growth direction. The multiple thin films become superlattices with the layer thicknesses varied randomly. They can be called disordered superlattices (d-SL) in contrast with a conventional, ordered superlattice (o-SL). The luminescence capability is remarkably enhanced by nonperiodic thicknesses. The photoluminescence (PL) intensities of AlAs GaA and Si Ge d-SLs are observed to be greater at least 500 times at 77 K and about 10 times at 10 K, respectively. The PL decays slow down with increasing temperature as compared with that of an o-SL. The physical mechanism for the unusual luminescence capability can be interpreted in terms of carrier localization caused by the nonperiodicity. Nonperiodic multiple thin films or d-SL can be considered as a promising material for the enhancement of the luminescence capability.