Purpose
The purpose of this paper is to investigate the effect of growth temperature on the evolution of indium incorporation and the growth process of InGaN/GaN heterostructures.
Design/methodology/approach
To examine this effect, the InGaN/GaN heterostructures were grown using Taiyo Nippon Sanso Corporation metal-organic chemical vapor deposition (MOCVD) SR4000-HT system. The InGaN/GaN heterostructures were epitaxially grown on 3.4 µm undoped-GaN (ud-GaN) and GaN nucleation layer, respectively, over a commercial 2” c-plane flat sapphire substrate. The InGaN layers were grown at different temperature settings ranging from 860°C to 820°C in a step of 20°C. The details of structural, surface morphology and optical properties were investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), atomic force microscopy and ultraviolet-visible (UV-Vis) spectrophotometer, respectively.
Findings
InGaN/GaN heterostructure with indium composition up to 10.9% has been successfully grown using the MOCVD technique without any phase separation detected within the sensitivity of the instrument. Indium compositions were estimated through simulation fitting of the XRD curve and calculation of Vegard’s law from UV-Vis measurement. The thickness of the structures was determined using the Swanepoel method and the FE-SEM cross-section image.
Originality/value
This paper report on the effect of MOCVD growth temperature on the growth process of InGaN/GaN heterostructure, which is of interest in solid-state lighting technology, especially in light-emitting diodes and solar cell application.
The current development of global warming and CO2 emission problems cannot be overlooked. Thus, global scale measures of efforts are becoming crucial. Thermal properties of insulation materials need to be considered as high performance thermal insulation systems are crucial for efficient energy saving. The most important parameter as indicator of a thermal insulation material is the effective thermal conductivity, but elements that affect the thermal insulation performance are rather complicated. Generally, conduction and radiation heat transfer are needed to be separately considered in precisely evaluating the thermal insulation performance as they coexist in the heat transfer process inside a multilayer insulation system. In this paper, numerical analysis of a complete diffusive enclosure model as a thermal insulation is observed to investigate the radiation effects by its dispersive heat transfer mechanisms. View factor of each relatively large dispersed material is derived in the enclosure model, where it is applicable to various shapes and any particular arrangements of dispersed materials. As this paper is the first part of a three-part working research paper, numerical analysis in this paper is carried out by assuming that the medium within the space inside the insulation system is taken to be nonparticipating, therefore conduction and convection effects during the heat exchange are negligible. This paper will be continued with application of the numerical analysis in observing radiation heating effects by wall-ceiling integration towards indoor environment and radiation–conduction heat transfer mechanisms in one-dimensional multilayer insulation system.
Gold nanoparticles (AuNPs) is known for its high surface area to volume ratio which acts as an excellent receptor when placed in between electrodes in sensors application. Microelectrodes which are bar and needle shape pointed ends with two arrangements; comb and castle wall configurations were designed to be used for fabrication of electrodes to observe the relation between geometry of electrodes and dielectrophoretic of AuNPs on p-gallium nitride (GaN) substrates. The dielectrophoretic behaviour and electrical properties were analysed before and after the drop cast of AuNPs using current-voltage (I-V) curve method with manual probing. Resistance values of each sample were calculated under reverse bias condition. The effect of design on the nanomanipulation of AuNPs will be discussed.
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