Optical absorption and determination of band offset in strain-balanced GaInP/InAsP multiple quantum wells grown by low-pressure metalorganic vapour phase epitaxy

Abstract

We report on optical absorption of the interband transitions in zero-net strained Ga x In 1−x P/InAs y P 1−y multiple quantum wells (MQW) grown by low-pressure metalorganic vapour phase epitaxy (LP-MOVPE), using tertiarybutylarsine as a group V source. Sharp interfaces are obtained using a growth interruption procedure. Analysis of this procedure with different interruption times leads to the same optimal times as those obtained for InP/InAsP superlattices grown in the same reactor. We have achieved the growth of modulation-free strain-balanced heterostructures, as indicated by cross-sectional transmission electron microscopy. High-resolution x-ray diffraction and optical absorption analysis demonstrate the high crystallographic and optical quality of these structures. The absorption spectrum of an x = 0.06, y = 0.14 sample was accurately fitted using the Bastard/Marzin model, and a strained conduction band offset of 94.0 ± 3.3 meV was deduced. This corresponds to about 75 ± 3% of the total strained bandgap difference.