Thin film transistor substrate for display panel

A display panel comprising:

• a first substrate having a base substrate;
• a gate electrode formed on the base substrate;
• a gate insulating layer including at least one of silicon nitride (SiNx) and silicon oxide (SiO2) formed on the base substrate to cover the gate electrode;
• a first surface treating layer formed on the gate insulating layer by treating the gate insulating layer with a nitrogen-containing gas including ammonia;
• an active layer formed on the first surface treating layer to cover the gate electrode, the active layer including amorphous silicon (a-Si);
• and
• a source electrode and a drain electrode spaced apart from the source electrode by a predetermined distance, the source and drain electrodes being formed on the active layer;
• a second substrate facing the first substrate;
• and
• a liquid crystal layer between the first substrate and the second substrate.