Growth of Fe doped semi-insulating GaN by metalorganic chemical vapor deposition

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Abstract
IrondopedGaN layers were grown by metalorganic chemical vapor deposition(MOCVD) using ferrocene as the Fe precursor. Specular films with concentrations up to 1.7×10 19 cm −3 , as determined by secondary ion mass spectrometry, were grown. The Fe concentration in the film showed a linear dependence on the precursor partial pressure, and was insensitive to growth temperature, pressure, and ammonia partial pressure. Memory effects were observed, similar to Mgdoping of GaN by MOCVD. The deep acceptor nature of Fe was used for growth of semi-insulating GaNfilms on sapphire substrates. A 2.6-μm-thick GaNfilm with a resistivity of 7×10 9 Ω/ sq was attained when the first 0.3 μm of the film was Fe doped. X-ray diffraction rocking curves indicated high crystalline quality, very similar to an undoped film, showing that Fe doping did not affect the structural properties of the film. Fe doping allows for growth of semi-insulating GaN on sapphire without the high threading dislocation densities and/or high carbon levels that are normally necessary to achieve insulating films.