Thickness Dependent Parasitic Channel Formation at AlN/Si Interfaces

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Gallium Nitride-on-Silicon (GaN-on-Silicon) electronic devices suffer performance degradation due to parasitic conduction pathways at the nitride-substrate interface.
• These parasitic channels cause increased switching losses and reduced breakdown voltages, hindering device efficiency.

Purpose of the Study:

• To investigate the physical nature and properties of the parasitic conduction channel at Aluminum Nitride/Silicon (AlN/Si) interfaces.
• To understand the thickness dependence of parasitic channel formation and its underlying mechanisms.

Main Methods:

• Secondary Ion Mass Spectroscopy (SIMS) was employed to analyze the origin of surface acceptor densities at the AlN/Si interface.
• Low-temperature (5 Kelvin) magneto-resistance (MR) measurements were conducted to probe the electronic properties of the interface.

Main Results:

• A strong thickness dependence of parasitic channel formation was observed, linked to increased surface acceptor densities in silicon.
• SIMS analysis identified Si-O-N complexes as the source of thermal acceptor formation.
• Magneto-resistance data indicated the presence of an electron inversion layer, contributing to parasitic conduction, though secondary at room temperature.

Conclusions:

• The study elucidates the critical role of silicon surface acceptors, specifically Si-O-N complexes, in forming parasitic channels at AlN/Si interfaces.
• Understanding these mechanisms is crucial for mitigating performance issues in GaN-on-Silicon electronic devices and optimizing their design.