Influence of light on individual defect noise in a -Si:H/ a -SiN x :H double barrier structures

A report on the influence of light on random telegraphic noise (RTN) in the current through a-Si:H/a-SiNx:H double barrier structures is given. Upon illumination with a focused He-Ne laser the spectral power density of the noise as well as the individual switching times are affected. Different regimes are observed: For sufficiently low light intensity the emission time constant τ̄e of the trap responsible for RTN decreases for increasing light intensity, whereas the capture time constant τ̄c remains nearly unaffected. For medium intensity illumination RTN disappears during illumination but recovers after its termination. Under high intensity illumination RTN vanishes and as a result the spectral power density of the unilluminated sample changes from a Lorentzian (typical for RTN) to a 1/f-like behavior. This unilluminated non-RTN state is metastable, i.e., the RTN state can be recovered by moderate thermal annealing.