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

Iron doped GaN layers were grown by metalorganic chemical vapor deposition (MOCVD) using ferrocene as the Fe precursor. Specular films with concentrations up to 1.7x10(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 Mg doping of GaN by MOCVD. The deep acceptor nature of Fe was used for growth of semi-insulating GaN films on sapphire substrates. A 2.6-mum-thick GaN film with a resistivity of 7x10(9) Omega/sq was attained when the first 0.3 mum 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. (C) 2002 American Institute of Physics.