Effect of Trap Behavior on the Reliability Instability of Metamorphic Buffer in InAlAs/InGaAs MHEMT on GaAs

Area of Science:

• Materials Science
• Semiconductor Device Physics
• Electronics Engineering

Background:

• Metamorphic high-electron-mobility transistors (MHEMT) grown on GaAs substrates offer potential advantages.
• Comparison with lattice-matched high-electron-mobility transistors (LM-HEMTs) is crucial for performance assessment.
• Understanding buffer layer influence is key to optimizing MHEMT performance.

Purpose of the Study:

• To evaluate the impact of the metamorphic buffer on MHEMT characteristics.
• To compare MHEMT performance against InP-based LM-HEMTs.
• To identify and quantify trapping effects influencing MHEMT device stability.

Main Methods:

• Direct current (DC) and radio frequency (RF) performance measurements.
• Pulsed I-V measurements to assess transient charging effects.
• Low-frequency noise (LFN) analysis and carrier-number-fluctuation (CNF) model for trap density extraction.

Main Results:

• MHEMTs exhibit comparable DC/RF traits to LM-HEMTs but with higher off-state current.
• Pulsed I-V measurements reveal significant drain current degradation in MHEMT due to fast transient charging.
• LFN analysis confirms bulk trapping as the dominant mechanism, with MHEMTs showing a substantially higher bulk trap density (3.56 × 10^17 eV⁻¹·cm⁻³) compared to LM-HEMTs (3.27 × 10^16 eV⁻¹·cm⁻³).

Conclusions:

• The metamorphic buffer in MHEMTs contributes to increased bulk trap density and transient charging effects.
• These effects lead to drain current degradation, impacting device stability.
• Further optimization of the metamorphic buffer is necessary to mitigate trapping and improve MHEMT reliability.