p-Channel GaN Transistor Based on p-GaN/AlGaN/GaN on Si

Abstract

In this letter, we demonstrate a recessed-gate p-channel MISFET using a p-GaN (70 nm)/Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.8</sub> N (15 nm)/GaN heterostructure grown by metalorganic chemical vapor deposition (MOCVD) on a Si substrate. A major benefit of such epi-structure is that it contains both a 2-dimensional electron gas (2-DEG) and a 2-dimensional hole gas (2-DHG), hence making it suitable for the GaN-based complementary circuit implementation. In addition, the 2-DEG at the interface of the AlGaN/GaN heterostructure is depleted due to the p-GaN layer on top giving rise to normally-OFF operation for the n-channel transistors. A contact resistivity of 4.9 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> Ω · cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is obtained for the ohmic contact to the hole channel for a p-GaN Mg concentration of 2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . Long channel (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> = 3 μm and L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sd</sub> = 9 μm) p-type transistors show an ON-OFF current ratio of ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> and ON resistance of ~2.3 kΩ · mm at VGS = -11 V.