Epitaxial growth of novel wide bandgap semiconductors and metallic diborides on silicon

Epitaxial SiCAlN films with wurtzite structure were grown on Si(111) by gas source molecular beam epitaxy via the reaction of H3SiCN precursor and Al atoms at 750°C, below the miscibility gap of SiC and AlN at 1900°C. The average hardness of the SiCAlN films is 25 GPa. Epitaxial SiCAlN was also grown on 6H-SiC(0001) substrates. Two structural models for the hexagonal SiCAlN films were constructed based on first-principles total-energy density functional theory calculations, showing agreement with the cross-sectional transmission electron microscopy images. The predicted fundamental band gap is 3.2 eV for stoichiometric SiCAlN film. Nonstoichiometric films of (SiC) x(AlN)1-x were synthesized on Si(111) for x = 0.40 to 0.80 and their and structural properties were analyzed.; Novel epitaxial thin films of metal-diborides were grown on Si(111) between 800 and 900°C as potential buffer layers for growth of group III-nitride semiconductors on silicon. Growth conditions and crystalline properties for HfB2, solid solutions of HfxZr1-xB 2 and AlxZr1-xB2 via thermal decomposition of unimolecular precursors Zr(BH4)4, Hf(BH 4)4, and Al(BH4)3 films were investigated. Basal plane growth was observed for all cases and the alloys exhibit a change in the a and c lattice parameter.; Growth of ZrB2 was also conducted on Si(001) substrate. The growth axis of the ZrB2 film lies along the [11&barbelow;00] direction. The difference between the crystal symmetry of ZrB2 and Si(001) produces two orthogonal domains and results in a 6:5 misfit for [112&barbelow;0] ZrB2//[11&barbelow;0]Si and a 13:12 misfit for [0001&barbelow;] ZrB2//[11&barbelow;0]Si on the interface plane. The island-substrate and island-island interfaces were examined in detail with high-resolution XTEM and compared with theoretical models.; Crystalline and epitaxial GaN films were grown on the ZrB2 buffer layers using D2GaN3. Basal-plane oriented growth of GaN was observed. GaN films produced weak photoluminescence peak at 365 nm and strong yellow emission at 10K. With the assistance of ultraviolet light during the deposition, the intensity of GaN photoluminescence increased and the full width of the half maximum of the 355 nm peak was 16.2 nm at 10 K.; Electron beam nanolithography of GaN dots was demonstrated using the D2GaN3 precursor on SiO2 and ZrB2 substrates in STEM. The smallest size of dot deposited from layer of adsorbed precursor was 4 nm and these dots were amorphous. Arrays of polycrystalline GaN dots were deposited using UHV-SEM at various conditions demonstrating a positive prospect of this instrument for electron lithography of GaN quantum dots.