Modeling the Effects of Threading Dislocations on Current in AlGaN/GaN HEMT

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Threading dislocations in AlGaN/GaN heterostructures are known to degrade device performance.
• These defects act as charge traps, influencing carrier transport and leakage currents.
• Understanding and modeling these effects are crucial for optimizing HEMTs.

Purpose of the Study:

• To develop a comprehensive model for the effects of threading dislocations on gate and drain currents in AlGaN/GaN HEMTs.
• To accurately capture the charge trapping/detrapping phenomena caused by dislocations.
• To precisely describe the reverse gate leakage current, particularly the Poole-Frenkel effect.

Main Methods:

• Modeling drain current drop using two simplified RC subcircuits with diodes to simulate trapping/detrapping.
• Incorporating trap voltages from RC networks into the drain current model.
• Developing a novel Poole-Frenkel (PF) model for reverse gate leakage current, considering acceptor-decorated dislocations.
• Implementing the physical parameter-based model in Verilog-A.

Main Results:

• The proposed model accurately predicts the decrease in drain current due to increased trap filling with threading dislocations.
• The model successfully captures the increase in gate leakage current, dominated by the Poole-Frenkel effect.
• The Verilog-A implementation shows excellent agreement with experimental data.

Conclusions:

• The developed model provides a physically accurate representation of threading dislocation effects on AlGaN/GaN HEMT electrical characteristics.
• This work offers a valuable tool for device simulation and optimization, enabling improved HEMT design.
• The accurate modeling of gate leakage and drain current degradation is essential for reliable high-power electronics.