Electroluminescent wavelength shift of Si-rich SiOx based blue and green MOSLEDs induced by O/Si composition Si-QD size variations

Electroluminescent (EL) color shift of Si-rich SiOx with its O/Si composition detuned by changing the RF plasma powers during N2O/SiH4 vapor deposition are investigated. The higher O/Si composition ratio of Si-rich SiOx films when enlarging the RF plasma power contributes to an increment of the insulating SiO2 resistivity and the shrinkage silicon quantum dots (Si-QDs), indicating the fewer injected carriers in Si-QDs. The increasing oxygen content in Si-rich SiOx shortens the diffusion length of Si atoms to constrain the buried Si-QD size. In contrast to the blue-shift of EL peak wavelength induced by enlarging the RF plasma powers, the lengthening deposition time causes a thicker Si-rich SiOx film with more excessive Si atoms, thus providing larger Si-QDs for longer wavelength EL. The EL spectra of metal-oxide-semiconductor light-emitting diodes are red-shifted with increasing the Si-rich SiOx thickness due to the varied Si-QD size and degraded electron conductivity. The uniformity of Si-QDs in Si-rich SiOx layer contributes to the obvious wavelength shift when applying the biased current. The EL peak has a slightly blue-shifted phenomenon when the biased current increases under the band filling effect. (C) 2013 Optical Society of America