INGAAS/INP QUANTUM-WELLS ON VICINAL SI(001) - STRUCTURAL AND OPTICAL-PROPERTIES

The growth of InGaAs/InP quantum wells (QWs) by low-pressure metalorganic chemical vapor deposition on vicinal Si(001) substrate is reported. Despite the fact that the etch pit density is about 2 X 10(7) cm-2 the low temperature (T = 2 K) luminescence efficiency is very high and about the same as for QWs grown at 640-degrees-C on InP substrates. The high efficiency is a result of the large structural perfection of the optically active QW areas. Microtwins (MTs) present a major source of nonradiative recombination in such structures. Transmission electron microscopy cross sections show a reduced growth rate within the MTs. A decrease of the QW width next to the boundaries leads to an increase of the effective band gap of the QW. Thus, local drift fields lead to a depletion of charge carriers close to the defects. The charge carriers in the QW are localized predominantly in defect-free areas and can efficiently recombine there radiatively. At room-temperature charge carriers are thermally activated to or remain in the narrower well regions next to the twin boundaries leading to enhanced nonradiative recombination and a comparatively larger drop of the quantum efficiency.