Effect of the active layer thickness on the electrical and electroluminescent properties in silicon rich oxide based light emitting capacitors

This work presents the electrical and electroluminescent properties of light emitting capacitors (LECs) using silicon rich oxide (SRO) films as active layer. Metal-insulator-semiconductor-like structures were fabricated with n+ polysilicon and aluminum as gate and substrate electrodes, respectively. SRO films were thermally annealed at high temperature to induce the silicon agglomeration. The effect of SRO thickness (tSRO = 24, 53 and 80 nm) on the electrical and electro-optical properties of LECs is analyzed. A high conduction state (HCS) is observed at low electric fields (E) for SRO films with 24 and 53 nm of thickness. The current drops from that HCS to a low conduction state (LCS) when a certain electric field is reached. The HCS at low E is not observed as the SRO thickness is increased. A broad visible electroluminescent spectrum is observed on LECs when the electric field is larger than 7.5 MV/cm2 through the Fowler-Nordheim mechanism. Moreover, an intense infrared (IR) electroluminescent peak is observed in LECs when the SRO film is decreased. This IR EL peak could be related with the silicon substrate emission.