Structural and optical properties of an InxGa1−xN/GaN nanostructure

Abstract

The structural and optical properties of an In x Ga 1Àx N/GaN multi-quantum well (MQW) were investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE) and photoluminescence (PL). The MQW structure was grown on c-plane (0 0 0 1)-faced sapphire substrates in a low pressure metalorganic chemical vapor deposition (MOCVD) reactor. The room temperature photoluminescence spectrum exhibited a blue emission at 2.84 eV and a much weaker and broader yellow emission band with a maximum at about 2.30 eV. In addition, the optical gaps and the In concentration of the structure were estimated by direct interpretation of the pseudo-dielectric function spectrum. It was found that the crystal quality of the InGaN epilayer is strongly related with the Si doped GaN layer grown at a high temperature of 1090°C. The experimental results show that the growth MQW on the high-temperature (HT) GaN buffer layer on the GaN nucleation layer (NL) can be designated as a method that provides a high performance InGaN blue light-emitting diode (LED) structure.

Structural analysis of an InGaN/GaN based light emitting diode by X-ray diffraction

“…2. The layer thicknesses and In content were measured by X-ray reflectivity and high resolution X-ray techniques in previous study [12]. At x = 0.096 value, a strong blue emission at 2.86 eV from photoluminescence spectrum is observed as shown in ref.…”

“…At x = 0.096 value, a strong blue emission at 2.86 eV from photoluminescence spectrum is observed as shown in ref. [12].…”

“…Generally, the size of the mosaic spreads can be evaluated from the peak widths of high resolution X-ray diffraction (HRXRD), which is characterized by the FWHM. In a previous study, the general optical and structural properties of this heterostructure were already reported [12]. The aim of the present paper is to investigate if the top InGaN/GaN multi quantum wells (MQWs) and p-GaN layer can influence the mosaic structure of the GaN buffer epi-layer.…”

Examination of the temperature related structural defects of InGaN/GaN solar cells

“…Furthermore, the growing parameters, surface dynamics and lattice structures are of significant importance for the development of nitride based optoelectronic and microelectronic devices. The temperature has a critical importance due to its effect on the lattice structures and the modification of the band range [12]. However, the studies performed with regards to the effect of temperature on the device performance are insufficient.…”

Development of 2" AlN Substrates Using SiC Seeds

“…Edge and mixed (screw/edge) dislocations in nitride materials act as nonradiative recombination centers and as conduits for charge transport resulting in leakage currents and breakdown (Amano et al, 2003;Davis et al, 2002). While high threading dislocation density is acceptable for light emitting diodes (LEDs) 6 -usually their small effect on the performance is attributed to the potential fluctuations related to the indium composition fluctuations (resulting from the poor In incorporation in the epitaxial layer during the growth or from the phase separation due to the large miscibility gap (I-hsiu & Stringfellow, 1996;Karpov, 1998;Korcak et al, 2007) ) observed in the active layers made from the ternary solid solution InGaN and in the corresponding QWs (Christen et al, 2003;Limb, 2007;Mukai et al, 2001) that provide the localization of carriers and reduce their in-plane diffusion to the non-radiative recombination centers -the high dislocation density, however, is fatal for laser diodes and power transistors; even for the LEDs including indium-free violet ones (Usikov et al, 2003) it leads to the drop in the efficiency and is the main factor of the device failure (Karpov, 2009;Roycroft et al, 2004 (Jain et al, 2000;Kukushkin et al, 2008;Miskys et al, 2003). Sapphire is a good choice for the nitride layers from the crystallographic point of view: crystal orientations of sapphire and gallium nitride grown on c-plane (0001) are parallel, with the unit cell of GaN being rotated by 30 • about c axis with respect to the unit cell of sapphire; the (1100) axis of GaN is parallel to the (1210) sapphire axis (Jain et al, 2000).…”