Improvement of Hydrogenated Amorphous-Silicon TFT Performances With Low-$k$Siloxane-Based Hydrogen Silsesquioxane (HSQ) Passivation Layer

A low-dielectric-constant (low-k)-material siloxane-based hydrogen silsesquioxane (HSQ) is investigated as a passivation layer in bottom-gate hydrogenated amorphous-silicon thin-film transistors (a-Si : H TFTs). The low-k HSQ film passivated on TFT promotes the brightness and aperture ratio of TFT liquid-crystal display due to its high light transmittance and good planarization. In addition, the performance of a-Si : H TFT with HSQ passivation has been improved, compared to a conventional silicon nitride (SiN
_x
)-passivated TFT because the hydrogen bonds of HSQ assist the hydrogen incorporation to eliminate the density of states between the back channel and passivation layer. Experimental results exhibit an improved field-effect mobility of 0.57 cm
²
/Vmiddots and a subthreshold swing of 0.68 V