Effect of photoexcitation on the surface band bending in delta-doped GaAs:Si/Al0.33Ga0.67As double heterostructures.

Photoluminescence spectroscopy in combination with electric-field-induced Raman scattering have been used to study the effect of photoexcitation on the surface electric field due to surface trap states in Delta-doped GaAs:Si/Alsub0.33Gasub0.67As double heterostructures. Upon variation of the optical power density over four orders of magnitude a continuous reduction of the surface electric field is found for increasing cw illumination. This is evident from a decrease of the electric-field- induced Raman signal and from a high-energy shift of the photoluminescence due to recombination of electrons at the Delta-doping layer with photogenerated holes localized at the topmost heterointerface. For the highest power densities of approximately equal to 10high3 W/qcm the electric field at that interface becomes almost zero indicating that band bending due to surface trap states is essentially removed.