Visible electroluminescence device by MOS structure with Si-implanted SiO_2

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Microdisplays become important in imaging, consumer, entertainment and data-graphic applications, such as camera viewfinders, head-mounted displays. A superior process compatibility with Si LSI makes Si-based light emitting devices attractive for the integrated intelligent displays in portable systems. Electroluminescence (EL) spectra under direct-current (dc) operation were studied for MOS capacitors with 50 nm Si-implanted SiO_2.The dc-EL intensity became about 50-70 times larger than the unimplanted MOS capacitor at the same current levels. Hysteresis curves in capacitance vs. gate voltage (C-V) characteristics were also observed for Si implanted capacitors. It suggests that the traps generated by Si-implantation cause the light emission. The ac-EL intensity was enhanced as the pulse frequency became higher in the frequency range from 10 Hz to 100 kHz. The longer components of the spectra were dominant.EL spectra under direct-current (dc) operation are reported for Au/SiO_2/p-Si MOS capacitors with 50 nm Si-implanted SiO_2. The Au film of 15 nm thick is transparent at 300 nm or longer wavelength and has the resistivity of 3 μΩcm. The transparent Au gate not only improves measurable wavelength range but also suppresses interference effects among MOS layers. The clear and smooth EL spectra were measured and the blue light emission was observed. The EL spectrum was analyzed by fitting five Gaussian distribution functions, i.e. hv=1.2, 1.6, 1.9, 2.4, 2.8 eV. These energy levels are related to the traps in Si-implanted SiO_2 A model of EL emission mechanism is proposed for the Si-implanted MOS EL device.