Electro-optical Properties of Non-stoichiometric Silicon Nitride Films for Photovoltaic Applications

The optical, electrical and electro-optical properties of metal-insulator-semiconductor (MIS) devices containing Si-rich silicon nitride (SRN) films are reported. The photoluminescence and optical absorption characterization evidences that optically active centers present a defective nature. As a consequence, a Poole-Frenkel type transport mechanism is considered, which is in agreement with the electrical results. The electro-optical performance of the devices has been found to be strongly modulated by the poly-Si electrode transmittance. After taking into account this contribution, EL emission has been studied, being the obtained spectra in accordance to the PL ones, which proofs that the same luminescent centers are also being excited electrically. The electrical response of the devices has been investigated under light excitation, showing induced photocurrent and photoconductivity, which makes SRN a good candidate material for photovoltaic applications.