UV electroluminescence from ITO/SRO/p-Si and ITO/SRN/SRO/p-Si structures

This work presents the electrical and electroluminescent properties of light emitting capacitors (LECs) using silicon rich oxide (SRO) and the effect of a thin silicon rich nitride (SRN) film on it (SRN/SRO) as active layers. LECs were fabricated using simple Metal-Insulator-Semiconductor (MIS) structures with indium tin oxide (ITO) and aluminum as gate and substrate electrodes, respectively. All devices exhibit a resistance switching (RS) behavior from a high conduction state (HCS) to a low conduction state (LCS), enhancing an intense ultraviolet-blue (UV-B) EL. This RS behavior produces structural changes in the active layer and probably in the ITO contact. Seven narrow bands with half-peak width of 7±0.6 nm at ∼250, 270, 285, 305, 325, 415 and 450 nm are clearly observed once the low conduction state is reached. The red-near infrared EL at HCS is similar to the PL spectra indicating the same radiative process is involved. An increment of the EL band at ∼590 nm in SRN/SRO is observed at both conduction states. This band has been observed before and attributed transitions from the minimum band conduction to K0 centers in SRN films. The UV-B emission appears at lower electric field when the SRN/SRO film is used as active layer.