Proton-induced fixed positive charge at the Si(100)-SiO2 interface

Area of Science:

• Materials Science
• Computational Physics
• Semiconductor Physics

Background:

• The Si(100)-SiO2 interface is crucial for semiconductor devices.
• Understanding interface defects is key to device performance and reliability.
• Proton-induced defects can impact electrical properties.

Purpose of the Study:

• To investigate the nature and origin of positively charged defects at the Si(100)-SiO2 interface induced by protons.
• To identify the specific atomic defect responsible for fixed positive charge during silicon oxidation.

Main Methods:

• Density-functional theory (DFT) calculations were employed.
• Realistic interface models were utilized to simulate the Si(100)-SiO2 system.
• Analysis of defect formation energies and bonding configurations.

Main Results:

• Protons induce defects by breaking strained bonds, forming threefold-coordinated silicon (Si(3)(+)) and oxygen (O(3)(+)) centers.
• Defect energies are within a 0.5 eV band, stabilized at the interface.
• Oxygen threefold-coordinated defects (O(3)(+)) emerge as deep defects at approximately 1 eV lower energy.

Conclusions:

• The O(3)(+) defect is identified as the most probable origin of fixed positive charge generated during silicon oxidation.
• The findings align with experimental observations and previous electrical data inferences.
• This work provides atomic-level insight into interface defect formation in Si/SiO2 systems.