No CrossRef data available.
Published online by Cambridge University Press: 01 February 2011
An optimization of growth parameters of Alx Ga1*x N/AlN/GaN heterostructure field effect transistors (HFET) grown by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) technique on SiC and sapphire substrates with relatively high Al mole fraction in the barrier layer (0.3 < x < 0.5) has been presented. The properties of the two-dimensional electron gas (2DEG) forming at the Alx Ga1-x N/GaN heterojunction can be tuned by careful adjustments of Alx Ga1-x N barrier layer thickness and Al mole fraction, x. The 2DEG sheet conductivities (μ n s ) as high as 2.6 × 1016 V-1s-1 at μ ∼ 2200 cm2/Vs and n s ∼ 1.2 × 1013 cm-2 has been achieved on Alx Ga1-x N/AlN/GaN HFET structures on SiC substrate at x = 0.47. HFET devices processed on these structures exhibited improved low field conductivities and DC and high frequency performance. Saturation currents above 1.2 A/mm at 0 V gate bias, transconductance as high as 340 mS/mm at Lg = 0.25 μm and FT × Lg > 20 GHz × μm were demonstrated on HFET structure grown on SiC substrates.