Thin film transistors with anodic gate dielectrics and chemical bath deposited active layers

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Abstract
Thin film transistors (TFTs) with an anodic dielectric layer and chemical bath deposited active layer have been fabricated on glass substrates. The effects of anodization conditions on the quality of the anodic dielectric were investigated by measuring the breakdown electric field and leakage current density of the metal–insulator–metal capacitors fabricated. Using the anodic gate dielectric, preliminary thin film transistors with CdS and CdSe films formed by a chemical bath deposition method were fabricated and evaluated. Results of electrical measurements carried out on the CdSe-TFTs with Al2O3 and Ta2O5 gate dielectrics showed field effect mobilities of 3.4 and 0.67 cm2/V s and threshold voltages of 3.2 and 8.2 V, respectively. Field effect mobilities of 0.2 and 2 cm2/V s and threshold voltages of 4.3 and 5.2 V were observed for CdS-TFTs, again with Al2O3 and Ta2O5 gate dielectrics. The mobilities obtained from the present TFTs fabricated on glass substrates are smaller than that on similar TFTs fabricated on thermally grown gate oxides on Si substrates in our previous work.