Title :
Influence of AlN Passivation on Dynamic ON-Resistance and Electric Field Distribution in High-Voltage AlGaN/GaN-on-Si HEMTs
Author :
Zhikai Tang ; Sen Huang ; Xi Tang ; Baikui Li ; Chen, Kevin J.
Author_Institution :
Dept. of Electron. & Comput. Eng., Hong Kong Univ. of Sci. & Technol., Hong Kong, China
Abstract :
We investigate in detail the influence of AlN passivation on dynamic ON-resistance (RON) and electric field (E-field) distribution in high-voltage AlGaN/GaN high electron mobility transistors (HEMTs) on a Si substrate based on pulsed I-V measurements, electroluminescence (EL) microscopy, and 2-D physics-based numerical device simulations. It is found that the dynamic RON increase has been significantly suppressed to below 10% at various temperatures ranging from -50 to 200 °C owing to the effective and robust compensation of deep acceptor-like trap states at the AlN/GaN (passivation/cap) interface by the additional positive polarization charges induced in the epitaxial AlN thin passivation layer grown in a plasma-enhanced atomic layer deposition system. To the best of our knowledge, this is the first time that highly suppressed current collapse in an AlGaN/GaN HEMT on a Si substrate within a wide temperature range is ever reported. By monitoring the dynamic RON for 100 consecutive 133-kHz switching cycles, its variation is observed to be less than 2.5%, indicating excellent stability of the passivation effectiveness. The electric field in an AlN-passivated device is found to be well confined at the drain-side gate edge, as shown in EL measurement and numerical simulation results. This phenomenon directly suggests that the virtual gate effect arising from surface trap charging has been effectively alleviated by the AlN passivation technique.
Keywords :
aluminium compounds; atomic layer deposition; electric fields; electroluminescence; elemental semiconductors; gallium compounds; high electron mobility transistors; microscopy; numerical analysis; physics; silicon; 2D physics-based numerical device simulations; AlGaN-GaN; AlN; EL measurement; EL microscopy; Si; cap interface; deep acceptor-like trap states; drain-side gate edge; dynamic on-resistance; electric field distribution; electroluminescence microscopy; epitaxial thin passivation layer; high electron mobility transistors; high-voltage HEMT; passivation effectiveness; plasma-enhanced atomic layer deposition system; positive polarization charges; pulsed I-V measurements; temperature -50 degC to 200 degC; virtual gate effect; HEMTs; III-V semiconductor materials; Logic gates; MODFETs; Passivation; Switches; Temperature measurement; AlGaN/GaN; AlN; charge compensation; current collapse; dynamic ON-resistance; electric field distribution; electroluminescence (EL); high electron mobility transistor (HEMT); high voltage; numerical simulations; plasma-enhanced atomic layer deposition (PEALD); polarization; pulsed (I) ?? (V); pulsed I-V; surface passivation; surface/interface states; surface/interface states.;
Journal_Title :
Electron Devices, IEEE Transactions on
DOI :
10.1109/TED.2014.2333063