Investigation of the interface properties of MOVPE grown AlGaN/GaN high electron mobility transistor (HEMT) structures on sapphire

• We have developed a virtual GaN substrate on sapphire based on a two-step growth method. By optimizing the growth scheme for the virtual substrate we have improved crystal quality and reduced interface roughness. Our Al0.22Ga0.78N/GaN HEMT structure grown on the optimized semi-insulating GaN virtual substrate, exhibits Hall mobilities as high as 1720 and 7350 cm(2)/Vs and sheet carrier concentrations of 8.4 x 1012 and 10.0 x 1012 cm(-2) at 300 K and 20 K, respectively The presence of good AlGaN/GaN interface quality and surface morphology is also substantiated by X-Ray reflectivity and Atomic Force Microscopy measurements. A simplified transport model is used to fit the experimental Hall mobility.

Nyckelord

MOVPE

HEMT

scattering

interface roughness

X-ray reflectivity

dislocations

CHEMICAL-VAPOR-DEPOSITION

GAN

HETEROSTRUCTURES

TECHNOLOGY

TEKNIKVETENSKAP

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