Nanocluster-rich silicon dioxide layers: electroluminescence and charge trapping Thoraif Gebel a

ABSTRACT Integrated optoelectronic devices are expected to become a key component of the future micro- electronic and communication technology. This has led to great interest in the development of silicon-basedlight emitters. Une of the most promising techniques for fabricating such emitters uses ion-beam synthesis(IBS) to form semiconductor nanoclusters in a layer of thermally-grown silicon dioxide. Following the preparation of metal-oxide-semiconductor (MOS) structures incorporating nanocluster-rich oxide layers, blue- to-violet electroluminescence (EL) has been observed at room temperature (RT) for implants using germanium ions and heat treatments involving furnace and/or rapid thermal processing. The power efficiencyof the EL is quite high, up to 5x103, making the blue/violet light emission visible with the naked eye. It hasbeen proven that light emission is caused by one and the same luminescent centre. The microstructure of theion-implanted and annealed oxide layers has been characterised by cross-sectional transmission electronmicroscopy (XTEM). The presence of second-phase nanoclusters has been found to modify considerably thecharge injection and charge transport in the oxide. The optical properties of the nanocluster-rich oxide layershave been correlated with the process of charge trapping using a combination of current-voltage (WV) andcapacitance-voltage (C/V) measurements. The results obtained have enabled the nature of the EL to be