Investigation of a Two-Layer Gate Insulator Using Plasma-Enhanced ALD for Ultralow Temperature Poly-Si TFTs

A two-layer oxide comprised of and grown at 150°C by atomic layer deposition (ALD) was investigated as the gate insulator for ultralow temperature poly-Si thin-film transistors (ULTPS TFTs). The two-layer gate insulator satisfied good interface quality and low leakage current at the same time. Using this material, n-channel ULTPS TFTs were fabricated on poly-Si with a threshold voltage of 2.3 V and a field-effect mobility of without hydrogenation.