Selective Passivation of GeO2/Ge Interface Defects in Atomic Layer Deposited High-k MOS Structures

Area of Science:

• Materials Science
• Semiconductor Physics
• Surface Chemistry

Background:

• Germanium metal-oxide-semiconductor (Ge MOS) devices are promising for next-generation electronics.
• Effective passivation of interface defects in high-k metal oxide/Ge gate stacks remains a significant challenge.
• Understanding interface properties is key to improving device performance.

Purpose of the Study:

• To investigate the formation of a germanium dioxide (GeO2) interface layer during forming gas anneal (FGA).
• To analyze the passivation of interface defects in Al2O3/Ge(100) gate stacks.
• To correlate GeO2 layer growth with interface trap passivation.

Main Methods:

• Photoelectron spectroscopy to probe the GeO2 interface layer.
• Capacitance-voltage and conductance-voltage measurements to extract interface trap density.
• First-principles modeling to study Ge/GeO2 and Ge/GeO/GeO2 structures and partial density of states (PDOS).

Main Results:

• Formation of a GeO2 interface layer was observed between Al2O3 dielectric and Ge(100) substrate during FGA.
• Selective passivation of interface traps in the upper half of the Ge band gap was achieved.
• Experimental results were corroborated by first-principles modeling.

Conclusions:

• Forming gas anneal can effectively passivate interface defects in high-k/Ge gate stacks through GeO2 formation.
• The study provides insights into defect passivation mechanisms in Ge MOS devices.
• This work contributes to the development of advanced germanium-based electronic devices.