Influence of Annealing Above the Deposition Temperature on Metastability in Amorphous Silicon

We have examined a thermally induced increase in the metastable defect density in a series of amorphous hydrogenated silicon samples deposited by the hot wire technique with different bonded hydrogen content. We observed a correlation between the excess defect density as measured after light soaking and as measured after thermal quenching. When the small H content (1-4 at.%) samples with reducedmetastability were annealed to above their deposition temperatures, they then displayed a significantly increased metastable defect density compared to their original values. We suggest that the microstructure of amorphous silicon determines the magnitude of metastability.