Measurement and Analysis of InGaN and InGaAlP High Brightness Light-Emitting Diodes
Date Issued
2007
Date
2007
Author(s)
Hung, Shang-Yu
DOI
en-US
Abstract
Recently High Brightness Light-Emitting Diode (HBLED) has been widely used and investigated. Nowadays GaN/InGaN and InGaAlP are the two most popular materials to made such a HBLED, just because the high efficiency [1].
For InGaN multiple quantum well (MQW), we get two 5QWs samples. The barrier and well width are almost the same (it can be proven by Transmission electron microscopy (TEM)), but the In composition of the InGaN quantum well is quite different. A series of PL measurement such as temperature dependent PL, power dependent PL, Time-resolved Photoluminescence (TRPL) are measured. In order to discus the peaks shift, quantum-confined Stark effect (QCSE), and localization effect of In-rich sample. X-ray diffraction (XRD) and Raman scattering also show us the sample’s quality.
For InGaAlP, we will first discuss the composition and the film quality to realize the characterization of InGaAlP thin films will be performed. And about the thin films, two series of (AlxGa1-x)0.5In0.5P films were grown on lattice-matched GaAs by low pressure MetalOrganic chemical vapor deposition under different conditions and studied by scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), photoluminescence (PL), photoreflectance (PR), X-ray diffraction (XRD), and Raman scattering. SEM shows the surface uniformity, EDX can calculate the composition of each atom. Comparative PL and PR measurements and analyses indicated the emission properties and the absorption properties. The degree of variations in compositions and film quality with the growth conditions were found from the spectral analyses. Raman spectral and XRD features are more sensitive to the sample growth parameter variations [2].
AlGaInP Material
The quaternary alloy (AlxGa1-x)0.5In0.5P, lattice-matched to GaAs and with a direct band-gap transition in the green-red light wavelength range, is an important material in visible light emitting diodes (LEDs) [3,4], laser diodes [5,6], heterojunction bipolar transistors (HBT) [7], matrix for the growth of self-assembled quantum dots (QDs) [8] and devices for 630-700 nm wavelength range applications such as laser pointers, barcode readers, digital versatile disk (DVD) players [9] and solid-state lighting [10]. Metalorganic chemical vapor deposition (MOCVD) technology has been widely employed for the growth and industry production of this quaternary and related materials [4, 5, 8, 9]. Atomic ordering may occur under certain conditions during the epitaxial growth of AlGaInP by MOCVD, which forms a Cu-Pt ordered structure, i.e. the group-III In, Ga and Al atoms spontaneously segregate into alternating {111} monolayers during growth rather than forming a disordered alloy with the In, Ga and Al atoms randomly distributed on all the group III sublattices [10,11]. This ordering results in the reduction of alloy bandgap and the negative effects in the subsequently grown devices. It is important to control and optimize the growth conditions to avoid or depress the appearance of ordering and other types of defects, to acquire high quality InGaAlP layers [2, 12].
Subjects
氮化銦鎵
磷化銦鎵鋁
LED
InGaN
InGaAlP
Type
thesis