Optoelectronic synapse with R, G, B light-driven plasticity. All colors induce synaptic modulation, with Blue showing the highest performance, followed by Green and Red.
Abstract
Amorphous oxide semiconductor (AOS)-based charge trap thin-film transistors (CTTFTs),
which are well-suited for 3D vertical stacking process, have emerged as a promising solution
for data-intensive neuromorphic applications. However, AOS-based CTTFTs face challenges
in erasing operations due to insufficient hole density in AOS channels. To address this issue,
we investigated the impact of the photoelectric effect on the erasing operation of amorphous
indium tin zinc oxide (a-ITZO)/ amorphous indium gallium zinc oxide (a-IGZO) CTTFTs
under illumination at various wavelengths of 650 nm (red), 532 nm (green), and 405 nm (blue).
We successfully demonstrated the fully erased state of a-ITZO/a-IGZO CTTFTs under blue
light, which has photon energy approximately equal to the a-ITZO/a-IGZO bandgaps. Additionally, the partially erased states were observed under green and red light, attributed to
the involvement of sub-gap states and band-tail states. The synaptic properties of a-ITZO/a
IGZO CTTFTs under blue light presented excellent linearity with nonlinearity factor (αp/αd) =
0.43/-0.72 and a wide dynamic range with conductance on/off ratio (Gmax/Gmin) = 483.9,
demonstrating a high pattern recognition accuracy of 93.44% in simulations using the MNIST
dataset. These results highlight the significant potential of a-ITZO/a-IGZO CTTFTs for
integrating low-power neuromorphic systems with display technologies by leveraging various
light sources in the visible wavelengths.
[Link to Journal website (ACS Applied Electronic Materials)]
Congratulations, Hyunji!