Epitaxial growth of p-type doped III-V nitride semiconductor on sapphire substrate using remote plasma metal organic chemical vapor deposition
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Lakehead University Remote Plasma-enhanced Metal Organic Chemical Vapour Deposition (RP-MOCVD) is used to grow III-V nitride semiconductor material. RP-MOCVD use nitrogen plasma as a nitrogen source along with group III precursor for epitaxial growth of III-V nitride. Using plasma for the growth process is advantages over conventional MOCVD as it uses ammonia for nitrogen source. As ammonia dissociate at higher temperature, restrict the growth for certain material thus limiting the selection of substrate for the growth process. RP-MOCVD is efficient as it operates at low temperature and uses plasma for growth. In this work p-type acceptor doped GaN epitaxial growth using RP-MOCVD is discussed. Mg is used as a dopant element to obtain p-type in GaN. Achieving p-type doping always remains a difficult issue for electronic and optical devices. Mg doped GaN has hole concentration around 1x1018 cm-3 due to saturation in p-type conductivity when Mg concentration is increased. Polarity of GaN matter during the growth, with Ga-polar GaN the hole concentration is higher compared with N-polar GaN. Temperature is one of the main factor in RP-MOCVD determining p-type conductivity in GaN film which provide room for compensation effect, solubility issue and dopant incorporation. The growth result obtained from RP-MOCVD are analysed using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Atomic force microscope (AFM), Hall effect, X-ray photoelectron spectroscopy (XPS).