Study of the Density of States of a-InGaZnO Using Field-Effect Technique

This paper studies the density-of-localized gap states (DOS) for RF sputter amorphous InGaZnO (a-IGZO) as determined from temperature dependent study of the a-IGZO thin film transistor (TFT) electrical properties. Measurements were performed on inverted-staggered RF sputter a-IGZO TFTs. The drain current (I_D) versus the gate-to-source voltage (V_GS) at different temperatures from 30degC up to 90degC were measured. Calculated DOS from the subthreshold regime appears to be low with a characteristic energy of about 110 meV. The DOS is larger and has a steeper slope with a characteristic energy of about 30 meV.