The main aim of this project is to carry out a critical and in depth study of electrical, optical and magneto transport properties of nitrogen containing III-V compounds such as bulk InN, In-rich Inl-xGaxK, GaN/lnN/Ga)J and n- and p- modulation doped Galni'1As QWs. Various experimental results presented and discussed provide fundamental important physical and electronic understanding which does not exist in the current literature such as a Superconductivity Phase transition in Mg-doped and unintentionally doped InN and also magnetotransport properties of modulation doped dilute nitrides. The plausible mechanisms are discussed in detail to explain the existence of the superconductivity in Mg and undoped InN samples. The optical properties of MBE grown III-nitrides and III-V-nitrides samples were investigated using steady state photoluminescence, Raman spectroscopy and spectral photoconductivity techniques while electrical properties were determined with Hall and magnetotransport measurements at low temperature T=1.6 K. The composition dependence of Longitudinal Optical (LO) phonon energies in undoped and Mg doped Inl_xGaxN samples are determined using two independent techniques in the range of Ga fraction from x=O to x=56%. The techniques used are the Raman and the temperature dependent momentum relaxation measurements at high temperatures where LO phonon scattering dominates the transport. The first study of spectral photoconductivity in Mg-doped indium rich GaxIn1_xK is presented. Spectral photoconductivity have three broad peaks at hw =0.65, 1.0 and l.4 eV. It is claimed that Indium segregation in the material might have occurred giving rise to three broad peaks in the photoconductivity spectra. The temperature dependence of the photoconductivity peaks suggest strongly that minority carrier trapping occurs in the material and the trapping energy of Erh=103±15meV is comparable to the Mg activation energy for InN .
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:528840 |
| Date | January 2010 |
| Creators | Gunes, Mustafa |
| Publisher | University of Essex |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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