InAs δ-layer structures in GaAs grown by MOVPE and characterised by luminescence and photocurrent spectroscopy

Abstract

Photocurrent, electroluminescence, and photoluminescence spectroscopy were used for the characterisation of laser structures containing ultrathin InAs δ-layers in GaAs matrix surrounded by AlGaAs waveguide and grown by low-pressure metal organic vapour phase epitaxy. Three types of δ-layer structures for laser active layers were investigated: single layers with different thickness ( W L), different numbers of identical layers ( N), and seven identical δ-layers separated by GaAs spacers of variable thickness ( S L). Measurement revealed two fundamental optical transition between electron and heavy and light hole states in the δ-layers. Both transitions are shifted to lower energies by hundreds of meV when W L and N increases or S L decreases. While the effect of W L can be explained by a quantum model accounting for the influence of stress and quantum state coupling, data obtained from multilayer structures exhibit significant deviation from theory.