Papers by Keyword: InGaN

Abstract: In this paper, InGaN/GaN/AlN/Si (111) structure was grown using a plasma-assisted molecular beam epitaxy (PA-MBE) technique. The structural and optical properties of grown film have been characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), high resolution X-ray diffraction (HR-XRD) and photoluminescence (PL). Indium-mole fraction has been computed to be 0.27 using XRD data and Vegards law with high grain size and low tensile strain. Room-temperature photoluminescence revealed an intense peak at 534 nm (2.3 eV) related to our sample In_0.27Ga_0.73N.

Abstract: This paper focuses on the compositional and structural characterization of InGaN-based light-emitting diode (LED) using high resolution x-ray diffraction (HRXRD) system. The LED was epitaxially grown on Si (111) substrate that comprises of In_0.11Ga_0.89N multi-quantum-well (MQW) active layer. Phase analysis 2θ-scan proved the composition of GaN (0002) and (0004) at 34.63^o and 72.98^o, respectively. Rocking curve φ-scan showed six significant peaks of the hexagonal GaN structures with consistent angular gaps of ~60^o. From x-ray rocking curve (XRC) ω-scan, screw and mix dislocation density is found as 2.85 × 10⁹ cm^-2, while pure edge dislocation density is found as 2.23 × 10¹¹ cm^-2.

Abstract: The Present Study Aims to Understand the Relation between the Nitridation and Indium-Composition of Ingan Grown on Sapphire Substrate Using the Metalorganic Vapor Phase Epitaxy through X-Ray Diffraction Reciprocal Space Mapping Measurements. In-Composition of InGaN on Nitrided Sapphire Substrate Increased to 13% which Is Higher than the Sample without Nitridation with 7%. Also, Flat Surface Was Observed in the Nitrided Sample. Two Times Larger in-Plane Strain Was Induced at the Nitired Sample. Ingan Grown on Low-Temperature Gan Buffer, however, Did Not Show Clear Effect of Nitridation. The Two Investigated Samples Showed Similar Indium Composition, Surface Flatness, and in-Plane Strain with and without Nitridation. Differences of Indium Incorporation and Relaxation of in-Plane Strain Were Attributed to the Effect of AIN Formed by Nitridation Process.

Abstract: Photoluminescence properties of InGaN film grown on sapphire substrates by metal organic chemical vapor deposition(MOCVD) was experimentally Investigation. The x-ray diffraction(XRD), transmission spectra, PL spectrum were used. The result of XRD shows that the mole composition of In in the InGaN film is estimated be 0.2 approximately. The band gap of the sample is calculated to be 2.66eV. A clear oscillation from F-P cavity could be observed on transmission spectra. There are three main peaks from the surface emission InGaN espaliers being excited on different light sources and different excitation power density. which can be explained the broad PL come from the difference of In composition modulated by was modulated due to F-P cavity arising from surface of sample. . It is found that there is some relationship between the position of the peaks in the PL spectra, the wavelength and intensity of power density and the F-P cavity.PACS: 73.61.

Abstract: In_xGa_1-xN epilayers have been grown by metalorganic chemical vapor deposition (MOCVD) at different temperatures between 740°C to 830°C. The thickness of InGaN film is 50nm for all samples. The incorporation of indium is found to increase with decreasing grown temperature. The optical properties and film quality of the samples have been investigated by photoluminescence (PL) system and X-ray diffraction (XRD). The Full Width at Half Maximum (FWHM) of PL and XRD decreases with increasing the grown temperature. We also found that the peak emission of PL shifts with changing the grown temperature. The effect of temperature on the film properties was determined. This understanding will lead to better quality control of the optoelectronic devices.

Abstract: Nitride materials are critical for a range of applications, including UV-visible light emitting diodes (LEDs). Advancing the performance, reliability and synthesis of AlGaN/GaN and InGaN/GaN heterojunction devices requires a systematic methodology enabling characterization of key metric like alloy composition, thickness and quality possibly in real time. This contribution reports on the real time characterization of the plasma assisted molecular beam epitaxy of AlGaN/GaN and InGaN/GaN heterostructures. Spectroscopic ellipsometry real time monitoring has revealed a number of key process and material iusses, such as the roughening of the GaN templates depending on plasma exposure during the substrate cleaning step, the composition of the alloy and the growth mode. Parameters like the plasma conditions, the surface temperature and the atomic flow ratio are investigated to understand the interplay process-material composition-structure-optical properties.

Abstract: We have studied InGaN single-quantum-well (SQW) films using atomic force microscopy (AFM) and cathodoluminescence (CL) spectroscopy. It has been found that a screw dislocations (SDs) distribution in the height image by AFM is well correlated with images of the CL spectra at about 440nm assigned to the spontaneous emission from the InGaN SQW. These results at least mean an existence of non-radiative recombination centers within the InGaN SQW films. It has been also found that the average period of the peak-intensity and the FWHM change is smaller than that of the peak-wavelength change assigned to InN mole fluctuations. These results suggest that the exciton diffusion length of the spontaneous emission at about 440nm is not larger than the average period of InN mole fluctuations in the InGaN SQW.

Abstract: We have measured cathodoluminescence (CL) spectra in the vicinity of V-defects in InGaN single-quantum-well(SQW) films at nanometer level, using newly developed CL apparatus (SE-SEM-CL). From spectroscopic CL measurement, it has been found that the spectra change dramatically in the vicinity of V-defects in the region of £50nm. The SE-SEM-CL has a potential to detect the CL spectral variation at spatial resolution with £50nm.

Abstract: We investigate critical thicknesses of InGaN epilayers grown on GaN substrates with the growth-plane not being the c-plane. In particular, we focus on non-polar orientations with growth planes being the m- and a-planes. We have taken into account the proper hexagonal symmetry of wurtzite GaN. We have found that there is only a small difference in the critical thickness for the cplane and the a-plane material; however, in the case of the m-plane material, we predict a quite different behaviour along the (in-plane) c-axis and the perpendicular (in-plane) a-direction.

Abstract: We review our recent experimental findings by optical orientation spectroscopy that show efficient spin relaxation within semiconductor spin detectors to be an important factor limiting efficiency of spin injection in spin light-emitting structures based on ZnCdSe/ZnMnSe and InGaN/GaMnN. We provide evidence for the physical mechanism responsible for the observed efficient spin relaxation that accompanies momentum and energy relaxation of excitons/carriers. These findings call for increasing efforts in suppressing spin relaxation in spin detectors.