Sub-gap excited photoluminescence in III-V compound semiconductor heterostructures

Photoluminescence (PL) above the excitation energy is observed in a single GaAs-InGaP quantum well (QW) and heterostructure as well as in a InP-GaAs superlattice (SL) and in strained layers. It is shown that sub-gap excitation (1.468 eV) of n-type delta-doped GaAs/GaInP quantum structure leads to an up-converted hot carrier PL emission with energy gains as high as 450 meV. The up-conversion energy in GaAs-InGaP heterostructures is 50 meV which is originated from the GaAs layer. In InP-GaAs SL, the sub-gap excitation results in a hot PL at 1.55 eV. It is also shown that the sub-gap excitation can be used to confirm the changes in band energies of a strained layer.