Photoinduced structural change and restoration of hydrogenated amorphous silicon

Polarized electroabsorption (PEA) measurements in the glancing-angle optical configuration have been performed on a-Si:H p–i–n diodes, aiming to re-examine our previous observation that the structural disorder is increased by light exposure. The new technique can minimize both the space-charge accumulation effects and the temperature modulation resulting from Joule heating which can have a significant impact on the PEA properties. Also the technique permits the actual photoinduced change in the PEA properties to be measured. The results show that the PEA intensity ratio, which is an indicator of structural disorder increases upon light exposure. This result verifies our previous conclusion. The dynamics of the change in the PEA disorder, internal stress, density and metastable defect density under light exposure have been systematically investigated to determine the link among them.