Polymorphous Silicon: A Promising Material for Thin-Film Transistors for Low-Cost and High-Performance Active-Matrix OLED Displays

Hydrogenated polymorphous Silicon allows to fabricate TFTs with very interesting characteristics including better threshold voltage stability than a-Si TFTs, lower leakage current than μc-Si:H TFTs and excellent uniformity. Investigation of threshold voltage shift mechanisms of pm-Si:H TFTs has shown a specific semiconductor material degradation with different activation energies compared to a-Si:H TFTs. TEM analysis has evidenced for the first time a significant structural difference between pm-Si:H and a-Si:H materials, in the TFT device configuration. Pm-Si:H appears to be very suitable for low cost and high performance AM-OLED fabrication. key words: thin-film transistors, polymorphous, silicon, OLED