The 3D wavy structure, with 2µm tall and 3µm wide "fins" repeated at a 6µm pitch give the channel a 70% larger operational width when compared with coplanar devices, allowing the wavy-channel TFTs (WC-TFT) to drive currents 70% higher per unit chip area.
By expanding the transistor's width vertically, through the implementation of grooved trenches, turn-on voltage or the OFF current values remain the same as traditional TFTs while benefiting from higher drive currents, the paper reports.
The researchers proved their new concept by fabricating WC-TFTs on a silicon substrate with ZnO/Al2O3/Al layers for the gate stack.
Once peeled off and transferred onto a flexible polydimethylsiloxane (PDMS) substrate, the transistors operated well with no degradation in their electrical performance or cracks in the gate stack even when flexed down to a bending radius of 5mm. “ON” current was only slightly lower, 10% lower than when bent to a radius of 1cm.