Enhanced Light Extraction from p-Si Nanowires/n-IGZO Heterojunction LED by Using Oxide-Metal-Oxide Structured Transparent Electrodes

Heterojunction light-emitting diodes (LEDs) comprising p-type Si nanowires (p-Si NWs) and n-type indium gallium zinc oxide (n-IGZO) were fabricated with the different top electrode materials: Al, indium zinc oxide (IZO), and IZO/ Ag/IZO oxide-metal-oxide (OMO) multilayer. All the LEDs exhibited typical rectifying behaviors of the p-n junction. Moreover, broad light-emission spectra in the visible range were observed because of the quantum confinement effect (QCE) of the Si NW and Si nanocrystals/nonstoichiometric Si oxide (SiOx) (x < 2) interfaces. In comparison to the LEDs with Al and single IZO electrode, the LED with the OMO multilayer electrode exhibited an enhanced optical performance because the OMO multilayer had an excellent transmittance of 87.7% in the visible range with a low sheet resistance of 5.65 Omega/sq. Furthermore, by investigating the transmittance spectra of the single IZO and OMO multilayer electrodes as a function of the light incidence angle, the OMO multilayer electrode is confirmed to be more suitable for white light emission from p-Si NWs/n-IGZO heterojunction LED.