0000000000135757
AUTHOR
Sylvain Nicolay
Lattice-Matched GaN–InAlN Waveguides at $\lambda=1.55\ \mu$m Grown by Metal–Organic Vapor Phase Epitaxy
We report on the demonstration of low-loss, single-mode GaN-InAlN ridge waveguides (WGs) at fiber-optics telecommunication wavelengths. The structure grown by metal-organic vapor phase epitaxy contains AlInN cladding layers lattice-matched to GaN. For slab-like WGs propagation losses are below 3 dB/mm and independent of light polarization. For 2.6-mum-wide WGs the propagation losses in the 1.5- to 1.58-mum spectral region are as low as 1.8 and 4.9 dB/mm for transverse-electric- and transverse-magnetic-polarization, respectively. The losses are attributed to the sidewall roughness and can be further reduced by the optimization of the etching process.
Indium surfactant effect on AlN/GaN heterostructures grown by metal-organic vapor-phase epitaxy: Applications to intersubband transitions
We report on a dramatic improvement of the optical and structural properties of AlN/GaN multiple quantum wells (MQWs) grown by metal-organic vapor-phase epitaxy using indium as a surfactant. This improvement is observed using photoluminescence as well as x-ray diffraction. Atomic force microscopy shows different surface morphologies between samples grown with and without In. This is ascribed to a modified relaxation mechanism induced by different surface kinetics. These improved MQWs exhibit intersubband absorption at short wavelength (2 mu m). The absorption linewidth is as low as 65 meV and the absorption coefficient is increased by 85%.
Optical, structural, and morphological characterisation of epitaxial ZnO films grown by pulsed-laser deposition
We report on ZnO epitaxial growth by pulsed-laser deposition (PLD) on different substrates, such as quartz, sapphire, and GaN template. Approximately 1 mu m-thick films were grown under different substrate temperatures and background oxygen conditions. X-ray diffraction analysis indicated preferential growth along the c-axis direction with a full-width at half maximum(FWHM) of the rocking curve as narrow as 230 arcs in the case of the GaN template. Low-temperature photoluminescence showed A-excitonic emission near 3.36 eV and a FWHM of (DXA)-X-0 emission as small as 2.89 meV at 9 K. Atomic force microscope measurements showed that roughness as low as 18 nm could be obtained. These results p…
Current status of AlInN layers lattice-matched to GaN for photonics and electronics
We report on the current properties of Al1-x InxN (x approximate to 0.18) layers lattice- matched ( LM) to GaN and their specific use to realize nearly strain- free structures for photonic and electronic applications. Following a literature survey of the general properties of AlInN layers, structural and optical properties of thin state- of- the- art AlInN layers LM to GaN are described showing that despite improved structural properties these layers are still characterized by a typical background donor concentration of ( 1 - 5) x 10(18) cm(-3) and a large Stokes shift (similar to 800 meV) between luminescence and absorption edge. The use of these AlInN layers LM to GaN is then exemplified …
Nitride-based heterostructures grown by MOCVD for near- and mid-infrared intersubband transitions
Intersubband (lSB) optical absorption in different nitride-based heterostructures grown by metal-organic chemical vapour deposition (MOCVD) is reported. The role of indium in AlInN/GaN multi-quantum wells (MQWs) is investigated. At high concentration (15%) AlInN is quasi lattice-matched to GaN and no cracks appear in the structure. At very low indium concentration (similar to 2%) the material quality is improved without decreasing the ISB transition wavelength with respect to the case of indium-free structures. Different mechanisms of strain relaxation in pure and 2% indium-doped AlN/GaN MQW structures are also investigated. ISB transition wavelengths of 2 urn for AlN/GaN MQWs, and 3 mu n f…
Mid-infrared intersubband absorption in lattice-matched AlInN/GaN multiple-quantum wells
We report the observation of midinfrared intersubband (ISB) absorption in nearly lattice-matched AlInNGaN multiple-quantum-wells. A clear absorption peak is observed around 3 μm involving transitions from the conduction band ground state to the first excited state. In addition to ISB absorption, photoluminescence experiments were carried out on lattice- matched AlInNGaN single quantum wells in order to determine the spontaneous polarization discontinuity between GaN and Al0.82 In0.18 N compounds. The experimental value is in good agreement with theoretical predictions. Our results demonstrate that the AlInNGaN system is very promising to achieve crack-free and low dislocation density struct…