Hydrogen diffusion and its electrical properties variation as a function of the IGZO stacking structure

Area of Science:

• Materials Science
• Semiconductor Physics
• Solid State Chemistry

Background:

• Oxygen vacancies and hydrogen are key charge carrier sources in oxide semiconductors.
• The precise carrier generation mechanism involving hydrogen and oxygen vacancies in amorphous indium gallium zinc oxide (a-IGZO) remains unclear.

Purpose of the Study:

• To investigate the influence of hydrogen on the electrical properties of a-IGZO thin films.
• To elucidate the variation mechanisms of electrical properties due to hydrogen diffusion from passivation layers.

Main Methods:

• Placing silicon oxide (SiOₓ) and silicon nitride (SiNₓ) passivation layers on a-IGZO to control hydrogen diffusion.
• Analyzing hydrogen penetration depth and its impact on the a-IGZO active layer.
• Observing changes in electrical resistivity and interfacial reactions.

Main Results:

• Hydrogen diffusion depth was sufficient to impact the entire a-IGZO layer.
• SiNₓ passivation led to a direct increase in a-IGZO electrical resistivity due to hydrogen.
• SiOₓ passivation induced different effects, including oxygen reactions and altered O-H bonding at the interface.

Conclusions:

• The bonding method of hydrogen and oxygen significantly influences the contribution of free electrons and thus electrical resistivity in a-IGZO.
• Passivation layer choice (SiOₓ vs. SiNₓ) critically determines the hydrogen-induced electrical property variations in a-IGZO semiconductors.