Ga2O3 is the only ultra-wide bandgap semiconductor with melt-growth substrate technology similar to that of Si, heterostructure device technology similar to that of the III-Nitride family, and high growth rate (GR) epitaxial technologies such as MOCVD and HVPE to support the development of ultra-high-breakdown voltage devices competitive with SiC technology. We report a Ga2O3 transistor device based on a high-GR MOCVD technology (Agnitron Technology’s Agilis 100 reactor). We have demonstrated for the first time a β-Ga2O3 MOSFET grown by high-GR MOCVD resulting in significantly improved epilayer quality. The high GR demonstrated via this method paves the road for demonstration of high breakdown voltage devices on a thick Ga2O3 buffer layer.
Ga2O3 is the only ultra-wide bandgap semiconductor with melt-growth substrate technology similar to that of Si, heterostructure device technology similar to that of the III-Nitride family, and high growth rate (GR) epitaxial technologies such as MOCVD and HVPE to support the development of ultra-high-breakdown voltage devices competitive with SiC technology. We have demonstrated for the first time a β-Ga2O3 MOSFET grown by high-GR MOCVD (Agnitron Technology’s Agilis 100 reactor) with record high mobility of 170 cm2/Vs, despite increased carrier scattering rate in the doped channel, facilitated by a significant improvement in epilayer quality. The high GR demonstrated via this method paves the road for demonstration of high breakdown voltage devices on a thick Ga2O3 buffer layer. [1] M.J. Tadjer et al., J. Phys. D: Appl. Phys. 54 (2021) 034005.
The realization of next-generation vertical GaN devices relies heavily on advances in both epitaxial growth of GaN drift layers on commercially available GaN substrates and selective area n-type and p-type doping in a planar process. Although homoepitaxial GaN is expected to provide more control over growth characteristics (e.g. crystallinity and doping), its reliability and reproducibility suffer at the hand of the native GaN substrates available to date. The variations in commercial GaN substrates span defect density, surface roughness, wafer bow, and photoluminescence properties. Thus, elucidating the role of GaN substrate properties on the growth and characteristics of resulting homoepitaxial GaN films has emerged as a new challenge towards next-generation GaN power devices. . In many other semiconductor materials such as Si and SiC, ion implantation is a routine step in most processing sequences for selective area doping and greatly facilitates manufacturing by avoiding the complicated etch/regrowth process. The ability to implant and activate dopants, particularly p-type dopants, in GaN still remains a challenge though. The NRL-developed symmetric multicycle rapid thermal annealing (SMTRA) technique has been shown to activate up to ~10% of the implanted Mg dopant atoms using a combination of a temporary thermally stable capping layer, annealing in a nitrogen overpressure, and performing a well-optimized annealing temperature profile including multiple spike anneals. This paper will present an assessment of substrate-dependent effects on the quality of homoepitaxial GaN films, evaluate ion implantation processing for selective area doping, address basic vertical devices to identify process module development toward practical MOSFET devices.
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