奈米光电半导体材料研究

1、PAGE I. CoverNational Taiwan University Excellence Research Program / Frontier and Innovative Research Program/Academia Industrial Corporation ProgramAnnual Report奈米光電半導體材料研究Nano Optoelectronics Semiconductor Materials(Grant No. 95R0061-AN00-03)PI: Chih-Chung (C. C.) Yang 楊志忠Co-PI: Ching-Fuh Lin 林清富

2、Lung-Han Peng 彭隆瀚Yean-Woei Kiang 江衍偉Zhe-Chuan Feng 馮哲川Jiun-Haw Lee 李君浩Chih-I Wu 吳志毅Jian Jang Huang 黃建璋Affiliation: Center for Advanced Nano-Materials (NTU-CANM)Overall Duration: Month 8 Year 2006 - Month 7 Year 2008 Report Duration: Month 8 Year 2006 - Month 7 Year 2008 November 4, 2008II. (Form1) B

3、asic Information of the ProgramProject Title: Nano Optoelectronics Semiconductor Materials奈米光電半導體材料研究Serial No.: 95R0061-AN00-03AffiliationCenter for Advanced Nano-Materials (NTU-CANM)尖端奈米材料中心Principal InvestigatorNameChih-Chung (C. C.) Yang楊志忠Program CoordinatorName(in English & Chinese)Tel:(02) 33

4、66-3643, 2365-7624Tel:Fax:(02) 2365-2637Fax:E-mailccy.twE-mailExpenditures1 (in NT$1,000)ProjectedActualFY 95FY 96OverallProject structure(Grant No.)TitlePrincipal InvestigatorTitleAffiliationMain Project(Grant No. 95R0061-AN00-03)Nano Optoelectronics Semiconductor Materials Structures奈米光電半導體材料研究Chi

5、h-Chung (C. C.) Yang楊志忠Professor教授CANM奈米中心(G. I. P. O光電所)Notes: 1 Please explain large differences between projected and actual figures.Project 3 Nano Optoelectronics Semiconductor Materials StructuresIII. (Form 2) Statistics on Research Outcome of this Program ListingTotalSignificant1RemarksPublish

6、ed ArticlesJournals11169Conferences306178Technology Reports0PatentsPending27-Granted10-Copyrighted InventionsItem0Workshops/Conferences2ItemParticipantsTraining Courses（Workshops/Conferences）Hours45ParticipantsPersonal Achievements Honors/ Awards3Keynotes Given by PIsEditor for JournalsTechnology Tr

7、ansfers Item2Licensing FeeNT$ 900,000RoyaltyIndustry Standards4ItemTechnological Services5Item-Service Fee-1 Indicate the number of items that are significant. The criterion for “significant” is defined by PIs of the project. For example, it may refer to Top journals (i.e., those with impact factors

8、 in the upper 15%) in the area of research, or conferences that are very selective in accepting submitted papers (i.e., at an acceptance rate no greater than 30%). Please specify the criteria in Appendix IV.2 Refers to the workshop and conferences hosted by the program.3 Includes Nobel Laureate, Mem

9、ber of Academia Sinica or equivalent, fellow of major international academic societies, and others.4 Refers to industry standards approved by national or international standardization parties that are proposed by PIs of the program.5 Refers to research outcomes used to provide technological services

10、, including research and educational programs, to other ministries of the government or professional societies.PAGE IV. (Form3) Executive Summary on Research Outcomes of this Program(Please state the followings concisely and clearly)1. General Description of the Project: Including Objectives of the

11、Project (overall)Subproject 3 The major research objectives of sub-project 3 include the use of various nano-material structures and nano-photonics techniques to enhance light emission efficiency for the applications of lighting, display, and optical storage. The used materials include nitrides, oxi

12、des, ferroelectrics, and organics. In nitrides, prestrained InGaN/GaN quantum wells and nano-columns are grown with MOCVD for fabricating phosphor-free efficient white-light light-emitting diodes. Also, GaN nano-cavities are formed for generating stimulated emission. In oxides, ZnO nanostructures ar

13、e used for efficient light emission. In ferroelectrics, 2-D nonlinear-optics photonic crystals are fabricated for converting long-wavelength laser into short-wavelength coherent light. In organics, novel organic light-emitting devices are to be invented. This sub-project includes eight members of fa

14、culty, covering the expertise of crystal growth, device process, material analyses, optical characterization, and numerical simulations. The major funding of this sub-project was used for purchasing shared equipment for device process. Breakthroughs and Major Achievements (please itemize for each su

15、b-project)Subproject 3 Coupling of an InGaN/GaN quantum well with surface plasmons for enhancing emission efficiency of a light-emitting diode by more than 100 %.Fabrication of white-light light-emitting diode based on red-light conversion of II-VI semiconductor nano-crystals and the enhancement of

16、conversion through localized surface plasmon coupling with the conversion efficiency higher than 50 %.Fabrication of phosphor-free white-light light-emitting diode with prestrained growth of InGaN/GaN quantum wells.Successful GaN nanocolumns and their coalescence overgrowth to achieve high-quality G

17、aN template.Systematic study of feature-controlled ZnO nanowire arrays via hydrothermal method showing the influences of ZnO sol-gel thin film characteristics on ZnO nanowire arrays prepared at low temperature using all solution-based processing.Numerical study on surface plasmon coupling with a rad

18、iating dipole using a plane-wave-assisted boundary integral-equation method.Reflective second harmonic generation from ZnO thin films: A study on the Zn-O bonding.By mixing the hole- and electron-transport layer materials as the host of the emitting layer, organic light-emitting devices with low dri

19、ving voltage and long lifetime were fabricated.Observation of 394 nm electroluminescence from low-temperature sputtered n-ZnO/SiO2 thin films on top of the p-GaN heterostructure.Demonstration of a domain reversal mechanism on Z-cut congruent-grown lithium tentalate (LiTaO3) composed of nickel (Ni) d

20、iffusion followed by pulse field poling.3. Categorized Summary of Research Outcomes. The criteria for top conferences and journals should be given and introduced briefly in the beginning of this section. Summary should be itemized for each sub-project. Note that the summaries should be consistent wi

21、th the statistics given in Form2.Subproject 3 (1) Coupling of an InGaN/GaN quantum well with surface plasmons for enhancing emission efficiencyThe coupling between a semiconductor QW and an SP can create an alternative channel of light emission besides that directly through carrier recombination. In

22、 this channel, the energy in carriers is first transferred into the SP modes, which are induced by the QW spontaneous emission on a metal structure nearby, through the coverage of the QW by the evanescent field of the SP mode, a process similar to stimulated emission. The SP modes can then be couple

23、d into radiation mode if the momentum matching condition is satisfied. Such a photon emission channel can be particularly effective when the SP energy loss is relatively lower than that through the non-radiative carrier recombination. In this situation, the spontaneous emission rate and the light ex

24、traction efficiency of a light-emitting device can be simultaneously enhanced. We have demonstrated the coupling effects between the QW and SP generated nearby on the p-type side in an InGaN/GaN single-QW light-emitting diode. The QW-SP coupling leads to the enhancement of the electroluminescence (E

25、L) intensity in the light-emitting diode sample designed for QW-SP coupling and reduced SP energy leakage, when compared to a light-emitting diode sample of weak QW-SP coupling or significant SP energy loss. In the light-emitting diode samples of significant QW-SP coupling, the blue shifts of the ph

26、otoluminescence and EL emission spectra are observed indicating one of the important features of such a coupling process. The device performance can be improved by using the n-type side for SP generation such that the device resistance can be reduced and the QW-SP coupling effect can be enhanced (by

27、 further decreasing the distance between the QW and metal) because of the higher carrier concentration in the n-type layer.Related publications:D. M. Yeh et al., “Localized surface plasmon-induced emission enhancement of a green light-emitting diode,” Nanotechnology 19, 345201 (2008).W. H. Chuang et

28、 al., “Differentiating the Contributions between Localized Surface Plasmon and Surface Plasmon Polariton on a One-dimensional Metal Grating in Coupling with a Light Emitter,” Applied Physics Letters 92, 133115 (2008).K. C. Shen et al., “Polarization dependent coupling of surface plasmon on a one-dim

29、ensional Ag grating with an InGaN/GaN quantum well,” Applied Physics Letters 92, 013108 (2008).J. Y. Wang et al., “Emission Enhancement Behaviors in the Coupling between Surface Plasmons on a one-dimensional Metallic Grating and a Light Emitter,” Applied Physics Letters 91, 233104 (2007).Y. C. Lu et

30、 al., “Enhanced Photoluminescence Excitation in Surface Plasmon Coupling with an InGaN/GaN Quantum Well,” Applied Physics Letters 91, 183107 (2007).D. M. Yeh et al., “Surface Plasmon Coupling Effect in an InGaN/GaN Single-quantum-well Light-emitting Diode,” Applied Physics Letters 91, 171103 (2007).

31、D. M. Yeh et al., “Surface Plasmon Leakage in Its Coupling with an InGaN/GaN Quantum Well through an Ohmic Contact,” Applied Physics Letters 91, 063121 (2007). J. Y. Wang et al., “Numerical study on surface plasmon polariton behaviors in periodic metal-dielectric structures using a plane-wave-assist

32、ed boundary integral-equation method,” Optics Express. 15, 9048-9062 (2007).D. M. Yeh et al., “Formation of various metal nanostructures with thermal annealing for controlling the effective coupling energy between surface plasmon and an InGaN/GaN quantum well,” Nanotechnology 18, 265402 (2007).Y. C.

33、 Lu et al., “Temperature dependence of the surface plasmon coupling with an InGaN/GaN quantum well,” Applied Physics Letters 90, 193103 (2007).C. Y. Chen et al., “Influence of the quantum-confined Stark effect in an InGaN/GaN quantum well on its coupling with surface plasmon for light emission enhan

34、cement,” Applied Physics Letters 90, 183114 (2007). C. Y. Chen et al., “Dependence of Resonant Coupling between Surface Plasmons and an InGaN Quantum Well on Metallic Structure,” Applied Physics Letters 89, 203113 (2006).(2) Fabrication of white-light light-emitting diode based on red-light conversi

35、on of II-VI semiconductor nano-crystalsWe have invented an alternative approach for fabricating phosphor-free high-color-rendering-index white-light light-emitting diode (LED) by using CdSe/ZnS nano-crystals for effectively converting blue/green photons into red light. Because such nano-crystals hav

36、e the advantages of spectral tunability, high quantum efficiency, and photo-stability, when compared with phosphors, they can be particularly attractive for red light conversion. We have implemented high-quality white light by coating such nano-crystals on a blue/green two-color LED. Recently, we ha

37、ve achieved 53 % conversion quantum efficiency by mixing Au nano-particles with the nano-crystals to induce the surface plasmon coupling with CdSe/ZnS nano-crystals for enhancing red conversion. In the coupling process, the surface plasmons on the Au nano-particles first absorb green light and then

38、effectively transfers the energy into the CdSe/ZnS nano-crystals for red emission. The aforementioned 53 % conversion efficiency is a record-high number for converting into red light from any shorter-wavelength light. Related publications:(a) D. M. Yeh et al., “White-light light-emitting device base

39、d on surface plasmon-enhanced CdSe nano-crystal wavelength conversion on a blue/green two-color light-emitting diode,” Applied Physics Letters 92, 091112 (2008).(b) H. S. Chen et al., “Mesa-size-dependent color contrast in flip-chip blue/green two-color InGaN/GaN multi-quantum-well micro-light-emitt

40、ing diodes,” Applied Physics Letters 89, 093501 (2006). (3) Phosphor-free white-light light-emitting diode with prestrained growth of InGaN/GaN quantum wellsWe invented a prestrain MOCVD growth technique for enhancing indium incorporation in growing InGaN/GaN quantum wells (QWs). The idea is to firs

41、t grow a low-indium InGaN layer or InGaN/GaN QW to generate tensile strain in the GaN barrier layer right above it. The tensile strain leads to the condition for easier indium incorporation in growing the subsequent InGaN/GaN QWs. Based on this technique, we have demonstrated the spectral red-shift

42、of the QWs designated for green emission into the orange-red range in a light-emitting diode (LED) by adding a violet-emitting QW at the bottom in MOCVD growth. An electro-luminescence red-shift of 53 nm was obtained. Based on the prestrain MOCVD growth technique, we have implemented a white-light I

43、nGaN/GaN QW LED epitaxial structure with its electroluminescence spectrum close to the ideal condition in Commission International de lEclairage chromaticity based on the presrained MOCVD technique. The prestrained growth leads to the efficient yellow emission from three InGaN/GaN QWs of increased i

44、ndium incorporation. The color mixing for white light is implemented by adding a blue-emitting QW at the top of the yellow-emitting QWs. The blue shifts of the blue and yellow spectral peaks of the generated electroluminescence spectra are only 2.2 and 11.6 nm, respectively, when the injection curre

45、nt increases from 10 to 60 mA. Related publications:(a) F. Huang et al., “Reduced injection-current-induced blue shift in an InGaN/GaN quantum-well light-emitting diode of prestrained growth,” Applied Physics Letters 91, 051121 (2007). (b) C. F. Huang et al., “Phosphor-free white-light light-emittin

46、g diode of weakly carrier-density-dependent spectrum with prestrained growth of InGaN/GaN quantum wells,” Applied Physics Letters 90, 151122 (2007).(c) C. F. Huang et al., “Prestrained effect on the emission properties of InGaN/GaN quantum-well structures”, Applied Physics Letters 89, 051913 (2006).

47、 (4) GaN nanocolumns and their coalescence overgrowthThis research team has been cooperating with US Air Force Research Laboratory for the study of GaN nanocolumns and their coalescence overgrowth. Such nanocolumns are almost threading dislocation free. We have accomplished high-quality coalescence

48、overgrown GaN layers. The crystal quality and light emission efficiency of such an overgrown GaN thin film are higher than those of a standard GaN thin film directly grown on sapphire substrate. Such overgrown GaN templates can be used for fabricating high-quality optoelectronics and electronics dev

49、ices. From an AFM measurement, the surface roughness is around 0.7 nm. From depth-dependent XRD measurement, it is found that three-beam XRD rocking-curve full-width at half-maximum in the (01-13)/(0-11-2) plane near the surface is around 4600 arcsec, which is significantly smaller than that of 6400

50、 arcsec in a high-quality GaN thin film directly grown on sapphire substrate. Also, from temperature-dependent photoluminescence measurement, it is found that the internal quantum efficiency of the overgrown sample is around 16.67 %, which is significantly higher than that of 7.04 % of the high-qual

51、ity GaN thin-film sample.Related publications:(a) W. Y. Shiao et al., “Characterizing the Thickness Dependence of Epitaxial GaN Grown over GaN Nanocolumns Using X-ray Diffraction,” J. Crystal Growth 310, 3159 (2008).(b) T. Y. Tang et al., “Coalescence Overgrowth of GaN Nano-columns with Metalorganic

52、 Chemical Vapor Deposition,” Nanotechnology 18, 445601 (2007). (5) Influences of ZnO sol-gel thin film characteristics on ZnO nanowire arrays prepared at low temperature using all solution-based processingThis work provides a systematic study of feature-controlled ZnO nanowire arrays via hydrotherma

53、l method. Our investigation demonstrates that the sol-gel thin-film pretreatment conditions have strong influences on the features of the ZnO nanowire arrays grown thereon. The annealing temperature of the ZnO sol-gel thin film can affect the microstructure of the ZnO grains and then the growth of t

54、he ZnO nanowire arrays. As the annealing temperature increases from 130 to 900 , the grain size of the thin films increases, and the diameter of thereon ZnO nanowire arrays increases from 60 to 260 nm. The thin films influence the nucleation of the ZnO and subsequently affect the diameter and orient

55、ation of the thereon nanowire arrays. At the temperature of 130 , the ZnO nanowire arrays align very vertically with growth along the c-axis direction. The PL measurements show a strong UV emission at 385nm, indicating that the low-temperature growth results in low levels of oxygen vacancies in the

56、nanowires. This work provides all solution-based processing route to fabrication of low-cost highly oriented ZnO nanowire arrays at low temperature. These vertical nanowire arrays are highly suitable for use in ordered nanowire-polymer devices, such as solar cells and light emitting diodes.Related p

57、ublication:(a) J. S. Huang et al., “Influences of ZnO sol-gel thin film characteristics on ZnO nanowire arrays prepared at low temperature using all solution-based processing,” J. Applied Physics 103, 014304 (2008). (6) Numerical study on surface plasmon coupling with a radiating dipole using a plan

58、e-wave-assisted boundary integral-equation methodA novel hybrid technique based on the boundary integral-equation method is proposed for studying the surface plasmon polariton behaviors in two-dimensional periodic structures. Considering the periodicity property of the problem, we use the plane-wave

59、 expansion concept and the periodic boundary condition instead of using the periodic Greens function. The diffraction efficiency can then be readily calculated once the equivalent electric and magnetic currents are solved that avoids invoking the numerical calculation of the radiation integral. The

60、numerical validity is verified with the cases of highly conducting materials and practical metals. Numerical convergence can be easily achieved even in the case of a large incident angle as 80o. Based on the numerical scheme, a metal-dielectric wavy structure is designed for enhancing the transmitta