2017 conference paper

Optimization of ALD high-k gate dielectric to improve AlGaN/GaN MOS-HFET DC characteristics and reliability

2017 IEEE 5th Workshop on Wide Bandgap Power Devices and Applications (WIPDA), 39–43.

By: F. Azam n, B. Lee n & V. Misra n 

co-author countries: United States of America πŸ‡ΊπŸ‡Έ
Source: NC State University Libraries
Added: August 6, 2018

This presents DC electrical characteristics and reliabilities of AlGaN/GaN metal-oxide-semiconductor heterojunction-field-effect transistors (MOS-HFETs) with HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gate dielectric deposited by atomic layer deposition (ALD). Two types of oxidants were investigated, namely, water (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O) and ozone (O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) for the ALD deposition. The comparison study reveals that GaN MOSHFETs with O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> oxidant results in overall better device performance and reliability than water based oxidant due to improved HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /GaN interface quality. For a 20nm ALD HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gate dielectric, MOS-HFET with O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> oxidant has less threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> ) shift with respect to HFET (1.8V), higher transconductance (112.66 mS/mm), less on-resistance, and less gate leakage (5.4Γ—10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) compared to MOS-HFET with water oxidant where V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> shift with respect to HFET is 9.15V, transconductance is 81.38 mS/mm and gate leakage is 1.7Γ—10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Moreover, significant improvement in device reliability (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> shift is less than 0.5V) is observed with O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> oxidant at high-temperature reverse bias (HTRB).