Impact of III-Nitride/Si Interface Preconditioning on Breakdown Voltage in GaN-on-Silicon HEMT

Abstract

In this paper, an AIGaN/GaN metal-oxide-semiconductor high-electron-mobility transistor (MOS-HEMT) device is realized. The device shows normal ON characteristics with a maximum current of 570 mA/mm at a gate-to-source voltage of 3 V, an on-state resistance of 7.3 Ω·mm and breakdown voltage of 500 V. The device has been modeled using numerical simulations to reproduce output and transfer characteristics. We identify, via experimental results and TCAD simulations, the main physical mechanisms responsible for the premature breakdown. The contribution of the AlN/Silicon substrate interface to the premature off-state breakdown is pointed out. Vertical leakage in lateral GaN devices significantly contributes to the off-state breakdown at high blocking voltages. The parasitic current path leads to premature breakdown before the appearance of avalanche or dielectric breakdown. A comparative study between a MOS-HEMT GaN on a silicon substrate with and without a SiNx interlayer at the AlN/Silicon substrate interface is presented here. We show that it is possible to increase the breakdown voltages of the fabricated transistors on a silicon substrate using SiNx interlayer.

Reduction in RF Loss Based on AlGaN Back-Barrier Structure Changes

“…ATLAS device simulation is based on comprehensive sets of models, including driftdiffusion transport models; energy balance and hydrodynamic transport models; Fermi-Dirac and Boltzman statistics; advanced mobility models; quantum transport models etc. [21,22]. In addition to the above comprehensive sets of models, ATLAS also has many specific built-in models suitable for different scenarios, among which we mainly use the low-field mobility model; the nitride-specific field-dependent mobility model; and the Shockley-Read-Hall (SRH) recombination and the Fermi-Dirac statistics models [23,24].…”

“…We set the electron lifetime as 1 × 10 −7 s and the hole lifetime as 1 × 10 −7 s. For GaN materials, the low-field electron mobility mun is set to 900, the low-field hole mobility mup is set to 10, the saturation electron velocity vsatn = 2 × 10 7 , the conduction band density at 300 k nc300 = 1.07 × 10 18 , and the valence band density nv300 = 1.16 × 10 19 ; for AlGaN Materials, mun = 600, mup = 10, nc300 = 2.07 × 10 18 , nv300 = 1.16 × 10 19 [21]; the AlGaN/GaN interface charge density is set to −1 × 10 13 , the electron surface recombination speed is set to 1 × 10 4 , and the hole surface recombination speed is set to 1 × 10 4 .…”