MIS p-GaN Tunneling Gate HEMTs on 6-In Si: A Novel Approach to Enhance Gate Reliability

To enhance gate swing and reduce gate leakage in p-GaN gate high electron mobility transistors (HEMTs), this work introduces novel metal-insulator–semiconductor (MIS) p-GaN tunneling gate HEMTs with an ultrathin Al2O3 tunneling layer. By varying the oxygen sources of atomic layer deposition (ALD), as well as the Al2O3 thickness of the MIS structure, we demonstrate the following results: 1) overdose hydrogen introduced by Al2O3 deposition using H2O as oxygen source severely deactivates the Mg dopants, negatively shifts the threshold voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {TH}}$ </tex-math></inline-formula>, and undermines the dynamic performance; 2) the MIS structure can effectively boost the forward bias gate breakdown voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {G-BD}}$ </tex-math></inline-formula>; 3) thick Al2O3 insulator of the MIS structure can, however, undermine the dynamic stability; and 4) MIS p-GaN tunneling gate HEMTs, with a 3-nm ultrathin Al2O3 insulator deposited using O3 as the oxygen source, exhibit an improved <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {G-BD}}$ </tex-math></inline-formula> from 12 to 13.2 V, a suppressed gate leakage, an optimized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {TH}}$ </tex-math></inline-formula> from 1.8 to 2.2 V, and unaffected <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {TH}}$ </tex-math></inline-formula> stability and dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {on}}$ </tex-math></inline-formula> performances. This work not only exposes the drawbacks of the traditional MIS p-GaN gate HEMTs but also proposes a novel MIS p-GaN tunneling gate structure to dedicatedly balance the static and dynamic performance, thus providing a new option for fabricating high-reliability HEMTs.