🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 5 of 5

Characteristics of emission polarization in a-plane nanorods embedded with InGaN/GaN multiple quantum wells
(2010-09-15)
Li, J. C.
;
Lu, T. C.
;
Huang, H. M.
;
Chan, W. W.
;
Kuo, H. C.
Nonpolar (a-plane) GaN nanorod arrays with embedded In(x)Ga(1-x)N/GaN (x=0.09, 0.14, 0.24, and 0.30) multiple quantum wells (MQWs) grown on r-plane sapphire have been fabricated successfully by self-assembled Ni nanomasks and subsequent inductively coupled plasma reactive-ion etching. After nanorod fabrications, the polarization ratio of the emission from MQWs with lower indium composition (x=0.09 and 0.14) slightly decreases but apparently increases by at most 79% for the samples with higher indium composition (x=0.24 and 0.30). Competition between the effect of multiple scattering, strain relaxation and reduction in localized centers, expected in a-plane MQW samples, are attributed to the variations in the polarization ratios after the nanorod formation. (c) 2010 American Institute of Physics. [doi:10.1063/1.3483239]
Characteristics of emission polarization in a-plane nanorods embedded with InGaN/GaN multiple quantum wells
(2010-09-15)
Li, J. C.
;
Lu, T. C.
;
Huang, H. M.
;
Chan, W. W.
;
Kuo, H. C.
Nonpolar (a-plane) GaN nanorod arrays with embedded In(x)Ga(1-x)N/GaN (x=0.09, 0.14, 0.24, and 0.30) multiple quantum wells (MQWs) grown on r-plane sapphire have been fabricated successfully by self-assembled Ni nanomasks and subsequent inductively coupled plasma reactive-ion etching. After nanorod fabrications, the polarization ratio of the emission from MQWs with lower indium composition (x=0.09 and 0.14) slightly decreases but apparently increases by at most 79% for the samples with higher indium composition (x=0.24 and 0.30). Competition between the effect of multiple scattering, strain relaxation and reduction in localized centers, expected in a-plane MQW samples, are attributed to the variations in the polarization ratios after the nanorod formation. (c) 2010 American Institute of Physics. [doi:10.1063/1.3483239]
Optical properties of a-plane InGaN/GaN multiple quantum wells on r-plane sapphire substrates with different indium compositions
(2009-03-15)
Chiu, C. H.
;
Kuo, S. Y.
;
Lo, M. H.
;
Ke, C. C.
;
Wang, T. C.
A-plane In(x)Ga(1-x)N/GaN (x=0.09, 0.14, 0.24, and 0.3) multiple-quantum-wells (MQWs) samples, with a well width of about 4.5 nm, were achieved by utilizing r-plane sapphire substrates. Optical quality was investigated by means of photoluminescence (PL), cathodoluminescence, and time resolved PL measurements (TRPL). Two distinguishable emission peaks were examined from the low temperature PL spectra, where the high- and low-energy peaks were ascribed to quantum wells and localized states, respectively. Due to an increase in the localized energy states and absence of quantum confined Stark effect, the quantum efficiency was increased with increasing indium composition up to 24%. As the indium composition reached 30%, however, pronounced deterioration in luminescence efficiency was observed. The phenomenon could be attributed to the high defect densities in the MQWs resulted from the increased accumulation of strain between the InGaN well and GaN barrier. This argument was verified from the much shorter carrier lifetime at 15 K and smaller activation energy for In(0.3)Ga(0.7)N/GaN MQWs. In addition, the polarization-dependent PL revealed that the degree of polarization decreased with increasing indium compositions because of the enhancement of zero-dimensional nature of the localizing centers. Our detailed investigations indicate that the indium content in a-plane InGaN/GaN MQWs not only has an influence on optical performance, but is also important for further application of nitride semiconductors.
High efficiency light emitting diode with anisotropically etched GaN-sapphire interface
(2009-07-27)
Lo, M. H.
;
Tu, P. M.
;
Wang, C. H.
;
Hung, C. W.
;
Hsu, S. C.
We report the fabrication and study of high efficiency ultraviolet light emitting diodes with inverted micropyramid structures at GaN-sapphire interface. The micropyramid structures were created by anisotropic chemical wet etching. The pyramid structures have significantly enhanced the light output efficiency and at the same time also improved the crystal quality by partially relieving the strain and reducing the dislocation defects in GaN. The electroluminescent output power at normal direction was enhanced by 120% at 20 mA injection current and the output power integrated over all directions was enhanced by 85% compared to a reference sample.
Lasing characteristics at different band edges in GaN photonic crystal surface emitting lasers
(2010-02-15)
Chen, S. W.
;
Lu, T. C.
;
Hou, Y. J.
;
Liu, T. C.
;
Kuo, H. C.
We have investigated the lasing characteristics of GaN-based two-dimensional photonic crystal surface emitting lasers (PCSELs) with different PC lattice constants by using angled resolved spectroscopy. Due to the Bragg diffraction theory, normalized frequency of lasing wavelength of PCSELs can be exactly matched with three distinct band-edge frequencies (Gamma 1, K2, and M3) in the photonic band diagram. The three band-edge frequencies (Gamma 1, K2, and M3) have different emission angles corresponding to the normal direction of the sample (0 degrees, 29 degrees, and 59.5 degrees).

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results