Hydrogenic impurities in superlattices with parabolic quantum well potentials

• Published in: Solid state communications 1985-01, Vol.55 (1), p.5-8
• Main Author: Luna-Acosta, Germán A.
• Format: Article
• Language: English
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/0038-1098(85)91093-2

Parabolic quantum-wells (PQWs) in compositional GaAs/Al xGa 1−xAs and homogeneous doping GaAs superlattices are being built using the technique of molecular beam epitaxy. The binding energy (Eb) and wave function of a hydrogenic impurity in an effective PQW are calculated variationally. Identifications of the parabolic coefficient K allows us to predict physical ranges of Eb. For typical compositional-PQWs, Eb depends logarithmically on the fraction of the conduction band discontinuity, Qe, hence appropriate experiments may be designed to confirm one of its two values (0.85 and 0.57) proposed elsewhere. Comparison with works of other authors indicates that 1) compositional-PQWs of typical widths (≳300Å) yield larger values of Eb compared to those of finite or even infinite square wells of same width, and 2) doping-superlattices with linear effective potentials produce physical ranges for |Eb| considerably larger than those obtained by doping-PQWs.