INTENSE ROOM-TEMPERATURE PHOTOLUMINESCENCE FROM NANOCRYSTALLINE Ge/SiO2 MULTILAYER STRUCTURES

Abstract

Hydrogenated amorphous Ge / amorphous Si multilayers with different thickness of sublayers were prepared on Si wafer by plasma-enhanced chemical vapor deposition and then oxidized at 800°C for various oxidation durations. Intense photoluminescence with multiple peaks was observed for the samples at room temperature. One peak is centered at the wavelength around 755 nm, which is almost unchanged from sample to sample and could be attributed to the luminescence from the defect states located at the interfaces between the formed nano-crystalline Ge and SiO 2. Another peak around 720 nm shows blue shift with increasing the oxidation duration, which may be deduced from the quantum confinement effect of nc-Ge. The luminescence from the samples with the same thickness of SiO 2 sublayers and different thickness of nc-Ge sublayers supported the suggested luminescence origin.