Hole transport via dangling-bond states in amorphous hydrogenated silicon nitride

Current transport through good quality undoped silicon-rich silicon nitride is normally limited by the contacts. However, if the concentration of silicon dangling bonds is increased by current stressing or raising the nitrogen content, current transport becomes bulk controlled and well described by the Poole–Frenkel effect in a defect band. Using thin-film diode structures on either p-type or n-type silicon substrates, we show that the I/V characteristics can only be explained if current transport in the defect bands within the silicon-rich nitride is via the movement of holes. Hole transport through defect states is probably a common feature in all the amorphous silicon-rich alloys.