Atmospheric pressure metalorganic vapor phase epitaxial growth and characterization of high quality GaN on sapphire (0001) substrates are reported. Using AlN buffer layers, thin films with optically flat surfaces free from cracks successfully grown. The narrowest x-ray rocking curve the (0006) plane is 2.70′ (202̄4) 1.86′. Photoluminescence spectra show strong near band edge emission. condition dependence crystalline also studied.

Transient capacitance methods were used to analyze traps occurring in unintentionally doped n-type GaN grown by hydride vapor-phase epitaxy. Studies deep-level transient spectroscopy (DLTS) and isothermal indicated the presence of three majority-carrier at discrete energies below conduction band with activation (eV) ΔE1=0.264±0.01, ΔE2=0.580±0.017, ΔE3=0.665±0.017. The single-crystal films on formed metal-organic chemical-vapor deposition sputter-deposited ZnO; a similar structure was found...

A Schottky barrier on unintentionally doped n-type GaN grown by hydride vapor phase epitaxy was obtained and characterized. Using vacuum evaporated gold as the contact aluminum for ohmic contact, good quality diodes were obtained. The forward current ideality factor n∼1.03 reverse bias leak below 1×10−10 at a of −10 V. height φBn determined to be 0.844 0.94 eV current-voltage capacitance measurements, respectively.

Optical measurements are performed near the fundamental absorption edge for single-crystal AlxGa1−x N epitaxial layers in composition range of 0≤x≤0.4. The dependence energy band gap on is found to deviate downwards from linearity, bowing parameter being b=1.0±0.3 eV. origin large discussed terms pseudopotential Al and Ga based Heine–Abarenkov type. With increasing x edges broaden, which attributed increase compositional nonuniformity.

InGaN films have been grown on GaN and AlGaN epitaxial layers by metalorganic vapor phase epitaxy. The “composition pulling effect” during the initial growth stages has studied as a function of lattice mismatch between underlying layer. crystalline quality is good near InGaN/GaN interface composition close to that GaN. However, with increasing film thickness, crystal deteriorates indium mole fraction increases. effect becomes stronger mismatch. It suggested atoms are excluded from early...

Epitaxial lateral overgrowth GaN structures oriented along the 〈112_0〉 direction were comprehensively characterized by cathodoluminescence (CL) microscopy and micro-Raman spectroscopy. CL directly visualizes significant differences between overgrown areas on top of SiO2 mask coherently grown regions stripes in quantitative correlation with spectroscopy mapping local strain free carrier concentration. The shows a partial relaxation high concentration that strongly broadens luminescence. A...

Deep levels in undoped and weakly Mg-doped n-type GaN films fabricated by metalorganic chemical vapor deposition were examined with deep level transient spectroscopy. measured at 0.26 0.62 eV below the conduction band found relatively low concentrations of ∼2×1013 cm−3 GaN. Addition small quantities Mg acceptor species means bis-cyclopentadienyl magnesium (Cp2Mg) during growth corresponded to a significant increase concentration eV. The shallower level, be independent Cp2Mg addition,...

Abstract The behaviour of catalyst free GaAs nanowire growth is investigated on (111)Si substrate by molecular beam epitaxy under different Ga and As fluxes. It found that the diameter increased increasing flux, while it decreased flux. rate along wire axis enhanced flux a constant Moreover, droplet at top disappears interruption strictly prohibited. By adopting last result, GaAs/AlGaAs core‐shell structure attempted. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We have dramatically enhanced the photoluminescence intensity emitted from a single quantum well (typically by factors of 3–6) covering sample surface with thin semitransparent metallic film. Using photolithographically prepared gold grating, we show that this enhancement is due to excitation plasmons on metal. By selectively turning off plasmon via or light polarization rotation, can be suppressed.

The selective metalorganic vapor-phase epitaxy of wurtzite GaN was performed on a (111) silicon substrate using SiO2 grid mask pattern. Within window regions (0.2–0.5) mm×(0.2–0.5) mm, films free from cracks were achieved. full width at half maximum the (0004) X-ray rocking curve as narrow 388 arcs and that band edge emission 18.6 meV 77 K. peak energy redshifted. redshift is reduced slightly in sample grown small windows. This suggests biaxial strain due to thermal expansion coefficient...

Al x Ga 1- N(0≦ ≦0.4) films grown on sapphires are found to be composed of many mosaic crystallites with various orientations by means double-crystal X-ray diffractometry. This fluctuation orientation can considerably reduced and the surface morphology (smoothness uniformity) film remarkably improved preceding deposition AlN buffer layers. A phenomenological model, which explain effect layer crystalline quality AlGaN films, is proposed.

Epitaxial layers of alloys are grown on sapphire (0001) and silicon (111) substrates by MOVPE in an ambient gas at atmospheric pressure. By optimizing the reactor design growth conditions, parasitic reactions metalorganic compounds with gaseous remarkably reduced composition can be controlled fairly well for first time. The vapor‐solid distribution coefficient Al is found to approximately unity. At respective substrate temperatures 1020°C 1050°C silicon, single‐crystal withx up 0.40...

A GaN pyramid grown selectively on a (111)Si substrate with patterned dot structure of SiO2 mask, by metalorganic vapor phase epitaxy using AlGaN as an intermediate layer, was characterized transmission electron microscopy. The pattern has array 5.0-μm-diameter window openings 10 μm period. density threading dislocations observed in the region decreased gradually increasing distance from interface. This mainly due to dislocation reaction and bending for first 2 interface upper region,...

Abstract MOVPE growth of uniform (11‐22)GaN layer was attempted on a patterned (113)Si substrate. The GaN achieved (1‐11) facets the Si selectively. optimum design substrate and conditions were studied to get semi‐polar with high optical crystalline quality. cathode‐luminescence spectra showed sharp edge emission peak which half width as narrow 10 meV. X‐ray rocking curves that (11‐22) diffraction 300 arcsec. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Schottky barrier contact using Au and ohmic Al were made on n-GaN grown by hydride vapour phase epitaxy. The diodes characterized in the range 77-373 K. Under forward bias, ideality parameter n=1.04 threshold voltage is 1.1 V. reverse bias leak current below 10-9 A a of -10 temperature-dependence I-V characteristics shows two regimes transport: one at low governed thermionic emission high-voltage regime due to spatial inhomogeneities metal-semiconductor interface. height phi B electron...