Browsing by Author "Ke, W. C."

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Growth and optical properties of high-density InN nanodots
(2010-10-15)
Ke, W. C.
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Lee, S. J.
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Kao, C. Y.
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Chen, W. K.
;
Chou, W. C.
High density InN/GaN nanodots were grown by pulsed mode (PM) metal-organic chemical vapor deposition (MOCVD). InN nanodots density of up to similar to 5 x 10(10) cm(-2) at a growth temperature of 550 degrees C was achieved. The high diffusion activation energy of 2.65 eV due to high NH(3) flow rate generated more reactive nitrogen adatoms on the growth surface, and is believed to be the main reason for the growth of high density InN nanodots. In addition, an anomalous temperature dependence of the PL peak energy was observed for high density InN nanodots. The high carrier concentration, due to high In vacancy (V(ln)) in the InN nanodots, thermally agitated to the conduction band. As the measurement temperature increased, the increase of Fermi energy resulted in blue-shifted PL peak energy. From the Arrhenius plot of integrated PL intensity, the thermal activation energy for the PM grown InN nanodots was estimated to be E(a)similar to 51 meV, indicating strong localization of carriers in the high density InN nanodots. (C) 2010 Elsevier B.V. All rights reserved.
Growth of optical-quality, uniform In-rich InGaN films using two-heater metal-organic chemical vapor deposition
(2013-11-15)
Fu, S. F.
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Chen, C. Y.
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Li, F. W.
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Hsu, C. H.
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Chou, W. C.
Good-optical-quality, thick InxGa1-xN films with high In content were grown using a homemade two-heater metal-organic chemical vapor deposition system. By varying the growth temperature, it was Found that the In composition of the InGaN epilayer varied from 18 to 59% as the substrate temperature decreased from 750 to 625 degrees C. Our results show that the optical properties in terms of the emission peak wavelength and linewidth are uniformly distributed throughout the entire 2 in. wafer for the x=0.40 InGaN sample. The resultant mean peak wavelength and FWHM are 808 +/- 6 nm and 229 +/- 18 meV, respectively, at 18 K. In addition, for the InGaN film grown at 625 degrees C, a noticeable decrease in the In composition occurred when the ceiling temperature was >800 degrees C, indicative of the occurrence of parasitic reactions in the gas phase. (C) 2013 Elsevier B.V. All rights reserved.
Impacts of ammonia background flows on structural and photoluminescence properties of InN dots grown on GaN by flow-rate modulation epitaxy
(2006-12-25)
Ke, W. C.
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Lee, L.
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Chen, C. Y.
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Tsai, W. C.
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Chang, W. -H.
Structural and photoluminescence (PL) properties of InN dots grown on GaN by metal organic vapor phase epitaxy using the flow-rate modulation technique, and their dependence on growth conditions, were investigated. An ammonia (NH3) background flow was intentionally supplied during indium deposition periods to control the kinetics of adatoms and hence the morphology of InN dots. Samples prepared under lower NH3 background flows generally exhibit narrower and more intense PL signals peaked at lower emission energies. The authors point out that the NH3 background flow is an important parameter that controls not only the nucleation process but also the emission property of InN dots. (c) 2006 American Institute of Physics.
Incorporation Behaviors of In and Ga in the Two-Heater MOVPE Growth of InGaN Films
(2016)
Fu, S. F.
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Cheng, C. H.
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Lee, F. W.
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Chen, S. Y.
;
Liao, B. W.
Incorporation behaviors of In and Ga of InGaN films grown by the two-heater metal-organic vapor-phase epitaxial horizontal reactor is investigated by varying growth parameters, such as the substrate temperature, ceiling temperature and reactor pressure. Two In loss mechanisms are observed by the analysis of the concentration and temperature profiles in the deposition zone. The gas-phase parasitic-loss mechanism (activation energy similar to 34.2 +/- 0.1 kcal/mol) is significant in the ceiling temperature T-ceil >= 800 degrees C and at substrate temperature (T-sub) of 600 degrees C. The decomposition-loss mechanism, which arises from In desorption on the growing surface, is significant in T-sub > 625 degrees C region. The desorption activation energy obtained is 28.0 +/- 0.1 kcal/mol, which is close to that of InN (25-26 kcal/mol). This suggests the In decomposition-loss mechanism in InGaN growth does not differ substantially from that in binary InN growth. On the other hand, the gas-phase parasitic-loss mechanism of Ga is negligible in the growth condition that we have explored. Exception is found for reactor pressure at T-ceil = 950 degrees C, where both factors advantageous and disadvantageous to Ga incorporation are unambiguously observed. We have proposed explanation for the above observation. (C) The Author(s) 2016. Published by ECS. All rights reserved.