Luminescent and electrical properties of PIN diodes based on a-Si1-xCx:H thin films

This work presents the study of the light emission and conduction mechanisms of PIN diodes using an amorphous silicon-carbide (a-Si1-xCx:H) thin film as active layer. The PIN structures were fabricated by the PECVD technique onto P-type silicon wafers at a substrate temperature of 200 °C. Two different active layers deposited with the CH4/SiH4 flow rates of 30 sccm/ 6sccm and 30 sccm/1 sccm were used. Both structures display red-orange electroluminescence only in forward bias. The structure deposited with a lower silicon content shows a shorter wavelength emission with a higher intensity at a lower voltage bias. From the current-voltage measurements the dominant charge transport mechanisms were proposed. On the one hand, the Fowler-Nordheim tunneling was related to the highest silicon content structure due to a lower barrier height, and on the other hand, the trap-assisted tunneling was associated with the lowest silicon content related to a higher density of defects in localized tail states.