High electric field response of wide bandgap a-Si:H photodiodes probed by transient current measurements

Abstract Diode devices n/i/Pt and n/i/p(Sb 2 S 3 ) were fabricated using high-quality wide bandgap a-Si:H (bandgap ∼1.85 eV) for the intrinsic photoactive layers to investigate high electric field transport of photoexcited carriers. Time-resolved photoresponse was examined by a transient current method. It was shown that primary and secondary photocurrents were distinguished by the transient photocurrent method. The n/i/Pt diode device showed a photocurrent gain as large as 10 3 but its response was slow, 5 ms, which is associated with secondary photocurrent. The use of p-type Sb 2 S 3 for electron blocking layer instead of Pt successfully suppressed the secondary photocurrent. Fast photoresponse with a response time 2 S 3 ) interface through a thermally-excited process.