Growth and characterization of doped GaAs/AlGaAs multiple quantum well structures on Si substrates for infrared detection

摘要

Doped GaAs/AlGaAs multiple quantum well structures were grown on Si substrates by molecular-beam epitaxy. The crystallinity of the epitaxial layers was examined by cross-sectional transmission electron microscopy and an x-ray rocking curve technique. The threading dislocation density of the multiple quantum well region was estimated to be 108 cm–2 by transmission electron microscopy. The x-ray rocking curve measurement revealed a full width at half-maximum of 380 arcsec, with no superlattice peak observed. Electrical and optical characterizations by tunneling current and intersubband infrared absorption showed comparable properties with similar structures grown directly on a GaAs substrate. The effect of crystallinity on the electrical and optical properties of the multiple quantum well structures is discussed.