Influence of the Built-in Piezoelectric Field on the Photoluminescence Spectra of Strained Superlattices InGaAs/GaAs on GaAs (110) and (111)A Substrates

10-period superlattices with pseudomorphic quantum wells {InxGa1-xAs/GaAs} with indium molar fractions x = 0.1 and 0.2 were grown by molecular beam epitaxy, each of them on GaAs substrates with crystallographic surface orientations (100), (110), and (111)A. A built-in piezoelectric field in the quantum wells of superlattices on GaAs (111)A substrates is formed in the direction perpendicular to the plane of the layers, and it causes a red shift of the peak in the photoluminescence spectrum compared to superlattices on conventional GaAs (100) substrates due to the quantum-confined Stark effect. This red shift increases with reducing photoexcitation power, as the photoexcited carriers screen the piezoelectric field. On the other hand, the peak in the photoluminescence spectra of superlattices on GaAs (110) substrates is not redshifted and does not change its energy position with a reducing in the photoexcitation power, since the piezoelectric field, even if it was formed, is directed laterally in the plane of the layers and does not cause quantum-confined Stark effect.