Step-graded AlGaN barrier engineering in AlGaN/GaN HEMTs for high-linearity low-noise RF amplifiers

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Device Physics

Background:

• High linearity is crucial for low-noise radio-frequency (RF) amplifiers.
• Conventional HEMTs face limitations in achieving enhanced linearity.
• Compositionally graded AlGaN barriers offer a potential solution for improved device performance.

Purpose of the Study:

• To propose and investigate a step-graded (SG) AlGaN/GaN HEMT structure.
• To analyze the impact of graded barriers on device linearity and performance.
• To optimize the SGHEMT design for enhanced DC/RF characteristics.

Main Methods:

• Systematic investigation of a step-graded (SG) AlGaN/GaN HEMT.
• Analysis of Al-composition effects on conventional HEMTs (CHEMTs).
• Exploration of barrier thickness and drain bias impacts on SGHEMT performance.

Main Results:

• The SGHEMT demonstrates improved and broader transconductance (g_m) and suppressed nonlinearities.
• Optimized SGHEMT (11 nm barrier) achieved g_m of 420.4 mS/mm and f_T of 154.3 GHz.
• Enhanced linearity and performance attributed to modified 2DEG confinement and carrier profile.

Conclusions:

• The proposed SGHEMT offers superior DC/RF performance and enhanced linearity.
• SGHEMTs are a promising candidate for high-linearity, low-noise RF amplifiers.
• Graded barriers effectively improve carrier confinement and device linearity.