Hybrid ZnO Core–a-Si:H Shell Infrared Photodetectors Integrated With Thin-Film Transistors

A novel lateral infrared photodetector was demonstrated using 3-D structures comprising of zinc-oxide nanowire (NW) cores and hydrogenated amorphous silicon (a-Si:H) thin-film shell. The 3-D infrared photodetectors showed a low dark current of ~10
^-11
- 10
^-12
A and ~10
²
- 10
³
light-on/light-off ratio with both constant and pulsed 1.55-μm wavelength light. A vertically integrated infrared sensor/thin-film transistor (TFT) device incorporating the 3-D infrared photodetector on the back channel of an a-Si:H TFT was fabricated, creating an integrated optical detector and a switch. The detector dark current was found to scale with the NW geometry on the TFT back channel and may be used to optimize the performance of the hybrid sensor-switch device.