OPTICAL STUDIES OF GAINP(ORDERED)/GAAS AND GAINP(ORDERED)/GAP/GAAS HETEROSTRUCTURES

We report on a detailed optical study of emission from a series of GaInP (ordered)/GaAs heterostructures. Some of these structures contain one or two thin (∼2 nm) layers of GaP between the GaInP and GaAs layers. A so-called “deep emission” band at 1.46 eV is observed in all our samples. However, at high excitation power, an emission above the band gap of GaAs (previously identified as quantum well emission) emerges only in structures where GaP layers are inserted on both sides in between the GaAs well and its GaInP barriers. From the pressure dependence we have identified the deep emission peak as due to donor–acceptor pair transitions at the GaAs/GaInP interface. The insertion of GaP layers between the GaInP (ordered) and GaAs layers helps to suppress the defects which contribute to this deep emission. By applying pressure to the sample which exhibits quantum well emission we have determined its band alignments. We show that the GaP layers form two effective barriers for confining electrons within the Ga...