Persistent photoconductivity due to trapping of induced charges in Sn/ZnO thin film based UV photodetector

Photoconductivity relaxation in rf magnetron sputtered ZnO thin films integrated with ultrathin tin metal overlayer is investigated. Charge carriers induced at the ZnO-metal interface by the tin metal overlayer compensates the surface lying trap centers and leads to the enhanced photoresponse. On termination of ultraviolet radiation, recombination of the photoexcited electrons with the valence band holes leaves the excess carriers deeply trapped at the recombination center and holds the dark conductivity level at a higher value. Equilibrium between the recombination centers and valence band, due to trapped charges, eventually stimulates the persistent photoconductivity in the Sn/ZnO photodetectors.

[1]  G. Heiland.  Photoconductivity of zinc oxide as a surface phenomenon , 1961 .

[2]  D. E. Brodie,et al.  Transparent conducting ZnO films deposited by ion-beam-assisted reactive deposition , 1992 .

[3]  S. Studenikin,et al.  Density of band-gap traps in polycrystalline films from photoconductivity transients using an improved Laplace transform method , 1998 .

[4]  Pierre Gibart,et al.  Si-doped AlxGa1-xN photoconductive detectors , 1999 .

[5]  H. Morkoç,et al.  A COMPREHENSIVE REVIEW OF ZNO MATERIALS AND DEVICES , 2005 .

[6]  J. Muth,et al.  Enhanced photoconductivity of ZnO films Co-doped with nitrogen and tellurium , 2005 .

[7]  N. Spaldin,et al.  Transition metal-doped TiO2 and ZnO—present status of the field , 2005 .

[8]  M. Schubert,et al.  Refractive indices and band-gap properties of rocksalt MgxZn1−xO (0.68⩽x⩽1) , 2006 .

[9]  Min Han,et al.  Wide-band gap oxide alloy: BeZnO , 2006 .

[10]  J. Zúñiga-Pérez,et al.  Structural characterization of a-plane Zn1−xCdxO (0 < x <0.085) thin films grown by metal-organic vapor phase epitaxy. , 2006 .

[11]  T. Murphy,et al.  Sub-bandgap photoconductivity in ZnO epilayers and extraction of trap density spectra , 2006 .

[12]  H. Yadav,et al.  Enhanced response from metal/ZnO bilayer ultraviolet photodetector , 2007 .

[13]  Dhananjay,et al.  Off-centered polarization and ferroelectric phase transition in Li-doped ZnO thin films grown by pulsed-laser ablation , 2007 .

[14]  H. Yadav,et al.  Study of metal/ZnO based thin film ultraviolet photodetectors: The effect of induced charges on the dynamics of photoconductivity relaxation , 2010 .