Browsing by Author "Tanikawa, Tomoyuki"

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Fabrication of InGaN/GaN Nanodisk Structure by using Bio-template and Neutral Beam Etching Process
(2015)
Lai, Yi-Chun
;
Higo, Akio
;
Lee, Chang Yong
;
Thomas, Cedric
;
Tanikawa, Tomoyuki
Quantum dot optoelectronic devices are very attractive for their low power consumption, temperature stability, and high-speed modulation. We developed a defect-less, top-down fabrication process for sub-12-nm diameter InGaN quantum nanodisks (NDs) embedded in GaN barrier by using a combination of a bio-template and neutral beam etching. We have achieved high density of 2.6 x 10(11) cm(-2) with 6-nm in diameter and 15-nm-high nanopillars.
Growth of semi-polar GaN-based light-emitting diodes grown on an patterned Si substrate
(2011)
Chiu, Ching-Hsueh
;
Lin, Da-Wei
;
Li, Zhen-Yu
;
Ling, Shih-Chun
;
Kuo, Hao-Chung
We present a study of semi-polar (1 (1) over bar 01) InGaN-based light emitting diodes (LEDs) grown on patterned (001) Si substrates by atmospheric-pressure metal organic chemical vapor deposition. A transmission electron microscopy image of the semi-polar template shows that the threading dislocation density was decreased significantly. From electroluminescence measurement, semi-polar LEDs exhibit little blue-shift and low efficiency droop at a high injection current because the reduction of the polarization field not only made the band diagram smoother but also restricted electron overflow to the p-GaN layer as shown in simulations. These results indicate that semi-polar InGaN-based LEDs can possess a high radiative recombination rate and low efficiency droop at a high injection current.
Nanometer scale fabrication and optical response of InGaN/GaN quantum disks
(2016-10-21)
Lai, Yi-Chun
;
Higo, Akio
;
Kiba, Takayuki
;
Thomas, Cedric
;
Chen, Shula
In this work, we demonstrate homogeneously distributed In0.3Ga0.7N/GaN quantum disks (QDs), with an average diameter below 10 nm and a high density of 2.1 x 10(11) cm(-2), embedded in 20 nm tall nanopillars. The scalable top-down fabrication process involves the use of self-assembled ferritin bio-templates as the etch mask, spin coated on top of a strained In0.3Ga0.7N/GaN single quantum well (SQW) structure, followed by a neutral beam etch (NBE) method. The small dimensions of the iron cores inside ferritin and nearly damage-free process enabled by the NBE jointly contribute to the observation of photoluminescence (PL) from strain-relaxed In0.3Ga0.7N/GaN QDs at 6 K. The large blueshift of the peak wavelength by over 70 nm manifests a strong reduction of the quantum-confined Stark effect (QCSE) within the QD structure, which also agrees well with the theoretical prediction using a 3D Schrodinger equation solver. The current results hence pave the way towards the realization of large-scale III-N quantum structures using the combination of bio-templates and NBE, which is vital for the development of next-generation lighting and communication devices.
Optical properties of (1 (1)over-bar 0 1) semi-polar InGaN/GaN multiple quantum wells grown on patterned silicon substrates
(2011-03-01)
Chiu, Ching-Hsueh
;
Lin, Da-Wei
;
Lin, Chien-Chung
;
Li, Zhen-Yu
;
Chen, Yi-Chen
We present a study of high quality (1 (1) over bar 0 1) GaN films and the InGaN/GaN multiple quantum wells (MQWs) using epitaxial lateral overgrowth (ELO) technique by atmospheric pressure metal organic chemical vapor deposition (MOCVD). The smooth coalescence of the stripes and surface morphology was measured by scanning electron microscope (SEM) and atomic force microscopy (AFM). Due to reduction in internal electric field, semipolar InGaN/GaN MQWs have higher radiative recombination rate from time-resolved photoluminescence (TRPL) measurement. In addition, from degree of polarization (DOP) measurement, we observed higher polarization ratio attributed to the induced anisotropic compressive strain. (C) 2010 Published by Elsevier B.V.
Reduction of Efficiency Droop in Semipolar (1(1)over-bar01) InGaN/GaN Light Emitting Diodes Grown on Patterned Silicon Substrates
(2011-01-01)
Chiu, Ching-Hsueh
;
Lin, Da-Wei
;
Lin, Chien-Chung
;
Li, Zhen-Yu
;
Chang, Wei-Ting
We present a study of semi-polar (1 (1) over bar 01) InGaN-based light emitting diodes (LEDs) grown on patterned (001) Si substrates by atmospheric-pressure metal organic chemical vapor deposition. A transmission electron microscopy image of the semi-polar template shows that the threading dislocation density was decreased significantly. From electroluminescence measurement, semi-polar LEDs exhibit little blue-shift and low efficiency droop at a high injection current because the reduction of the polarization field not only made the band diagram smoother but also restricted electron overflow to the p-GaN layer as shown in simulations. These results indicate that semi-polar InGaN-based LEDs can possess a high radiative recombination rate and low efficiency droop at a high injection current. (C) 2011 The Japan Society of Applied Physics
Reduction of Efficiency Droop in Semipolar (1(1)over-bar01) InGaN/GaN Light Emitting Diodes Grown on Patterned Silicon Substrates (vol 4, 012105, 2011)
(2011-03-01)
Chiu, Ching-Hsueh
;
Lin, Da-Wei
;
Lin, Chien-Chung
;
Li, Zhen-Yu
;
Chang, Wei-Ting