Recent advances in the growth, doping and characterization of III-V nitride thin films.
In: Advances in Solid State Physics 35; 1995, p1-24, 24p
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Zugriff:
Boron nitride thin films have been grown on the (100) surfaces of Si and diamond via ion beam assisted deposition (IBAD) using electron beam evaporation of B in tandem with N and Ar ion bombardment within the ranges of substrate temperature and ion flux of 200-700°C and 0.20-0.30 mA/cm2, respectively. Fourier-transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM) revealed a growth sequence of amorphous (a-BN), hexagonal (h-BN) and cubic (c-BN) layers under most conditions. This sequence is attributed primarily to increasing biaxial compressive stress with film thickness due to ion bombardment and some interstitial Ar incorporation. A minimum substrate temperature of 200-300° C is required for nucleation and growth of single phase c-BN by this technique. The initial stage of AlN film growth on α(6H)-SiC(0001) substrates by plasma-assisted, gas source molecular beam epitaxy has been investigated in terms of growth mode and interface defects. Essentially atomically flat AlN surfaces, indicative of two-dimensional growth, were obtained using on-axis substrates. Island-like features were observed on the vicinal surfaces. The coalescence of latter features gave rise to double positioning boundaries as a result of the misalignment of the Si/C bilayer steps with the Al/N bilayers in the growing films. The quality of the thicker AlN films was strongly influenced by the concentration of these boundaries. Monocrystalline GaN and AlxGa1−xN(0001) (0≤x≤1) films, void of oriented domain structures and associated low-angle grain boundaries and with smooth surface morphologies, have been grown via OMVPE on high-temperature monocrystalline AlN(0001) buffer layers, previously deposited on vicinal α(6H)−SiC(0001) wafers, using TEG, TEA and ammonia in a cold-wall, vertical, pancake-style reactor. Abrupt heterojunctions were demonstrated. The PL spectrum of the pure GaN showed strong near band-edge emissions with a FWHM value of 4 meV. Cathodoluminescence spectra of AlxGa1−xN films for x<0.5 also showed intense near band-edge emission. The dislocation density within the first 0.5 μm was ≈1×109 cm−2; it decreased substantially with increasing film thickness. Double-crystal XRC measurements indicated a FWHM value of 66 arc sec for the pure GaN(0004) reflection; the value of this parameter increased with increasing values of x. Controlled n-type Si-doping of pure GaN has been achieved for net carrier concentrations ranging from approximately 1×1017 cm−3 to 1×1020 cm−3. As-deposited Si-doped Al0.75Ga0.25N exhibited negative electron affinity. Mg-doped, p-type GaN was achieved with nA−nD≈3×1017 cm−3, ρ≈7 Ω·cm and μ≈3 cm2/V·s. [ABSTRACT FROM AUTHOR]
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Titel: |
Recent advances in the growth, doping and characterization of III-V nitride thin films.
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Autor/in / Beteiligte Person: | Helbig, Reinhard ; Davis, Robert F. ; Ailey, K. S. ; Bremser, M. D. ; Carlson, E. ; Kern, R. S. ; Kester, D. J. ; Perry, W. G. ; Tanaka, S. ; Weeks, T. W. |
Quelle: | Advances in Solid State Physics 35; 1995, p1-24, 24p |
Veröffentlichung: | 1995 |
Medientyp: | Buch |
ISBN: | 978-3-528-08043-3 (print) |
DOI: | 10.1007/BFb0107537 |
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