RESEARCH in highly efficient visible color light emitting

Transcription

1 JOURNAL OF DISPLAY TECHNOLOGY, VOL. 12, NO. 9, SEPTEMBER Multifacet Microrod Light-Emitting Diode With Full Visible Spectrum Emission Yun-Jing Li, Jet-Rung Chang, Shih-Pang Chang, Bo-Wen Lin, Yen-Hsien Yeh, Hao-Chung Kuo, Fellow, IEEE, Yuh-Jen Cheng, and Chun-Yen Chang, Life Fellow, IEEE Abstract We demonstrated a full visible spectrum emission from a 3D multifacet microrod light-emitting diode (LED). The microrods were fabricated by top-down patterned etched and regrowth. Hexagonal {11-20} and {11-22} facets were first formed on the microrods, then gradually transformed to {10-10} and {10-11} facets. This facet evolution was attributed to the growth competition among different crystal planes. The multiple quantum wells grown on the microrods also followed this facet evolution and resulted in broad emission spectrum. The device can have direct white light emission covering full visible spectral range from 460 to 660 nm under electrical injection. Index Terms Gallium nitride, light emitting diode, multiple quantum wells, semipolar. I. INTRODUCTION RESEARCH in highly efficient visible color light emitting diodes (LEDs) plays an important role in the development of the next generation lighting and display applications [1] [3]. InGaN compound semiconductors have been extensively studied and are widely seen as promising materials for multiple-color lighting devices. The band gap can be potentially varied from UV (3.4 ev) to near infrared (0.7 ev). In principle, InGaN devices can cover the whole visible spectrum. Conventional GaN/InGaN multiple quantum well (MQW) LEDs are often grown on a c-plane sapphire substrate. The polar nature of this crystal surface induces a strong piezo polarization field in MQWs due to GaN-InGaN lattice mismatch, which causes electron-hole (e-h) wave function separation. This effect reduces e-h recombination efficiency especially when the In composition in InGaN QW increases for long wavelength emissions. This limits the range of emission wavelength. One way to solve this problem is to grow MQWs on other crystal planes Manuscript received March 16, 2016; revised April 14, 2016; accepted April 20, Date of publication April 27, 2016; date of current version August 15, This work was supported in part by the Ministry of Science and Technology of Taiwan under Contract MOST M Y.-J. Li and C.-Y. Chang are with the Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan ( ffmamie@gmail.com; cyc@mail.nctu.edu.tw). J.-R. Chang is with Taiwan Semiconductor Manufacturing Company, Hsinchu 30010, Taiwan ( schumiee94g@gmail.com). S.-P. Chang is with National Nano Device Laboratories, Hsinchu 30078, Taiwan ( spchang7168@gmail.com). B.-W. Lin and H.-C. Kuo are with the Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan ( lbwferro@gmail.com; hckuo@faculty.nctu.edu.tw). Y.-H. Yeh and Y.-J. Cheng are with Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan ( a @gmail.com; yjcheng@gate.sinica.edu.tw). Color versions of one or more of the figures are available online at Digital Object Identifier /JDT with low or no polarization field, e.g., semipolar or nonpolar crystal surfaces. However, large area substrates of these crystal planes are not readily available. An alternative method to access these crystal planes is by three-dimensional (3D) crystal growth from a c-plane substrate. LEDs grown on 3D structures, such as micro-stripes [2], nanorods [4], [5], pyramids [6] [11] have thus attracted great research interests. The 3D structure allows InGaN MQWs to be grown on crystal planes with low or no polarization field. They can potentially incorporate high In composition and still maintain reasonable e-h recombination efficiency [12]. The 3D MQW structure can potentially incorporate high In composition and still maintain reasonable e-h recombination efficiency. The shapes of 3D structures can be controlled by growth parameter and substrate patterning [13] [15]. MQWs grown on the facets can have different In compositions and varying well thickness to emit multiple colors [6]. The LED using 3D structure MQWs can potentially be designed to have emission covering the full visible spectrum without relying on phosphor down conversion. The realization of such a device is however still under development. So far, the reported emission spectrum from an individual LED spans at most slightly over 100 nm toward green in visible spectrum [2], [3], [5] [9]. Here, we report the demonstration and study of an electrically driven microrod LED that can have emission covering over 200 nm from blue to red (470 to 670 nm) right in the full visible spectral range. II. EXPERIMENTAL DETAILS The fabrication flow of microrod LED is shown in Fig. 1(a). n-gan microrods were first prepared by lithography patterning and etching processes from a 2 μm thick n-gan template grown from a c-plane sapphire substrate. The top-view and tilted view SEM images of the fabricated n-gan microrods are shown in Fig. 1(b) and (c), respectively. The n-gan microrod array has a pitch of 4 μm, a diameter of 2 μm, and a height of 1μm. The microrod LED and a c-plane planar reference sample were then loaded into a MOCVD chamber to grow MQW LED structure. A thin n-gan layer was grown first to repair surface damage from the top-down etching process. The re-grown microrods reveal multiple crystalline facets, as shown in Fig. 1(d) and (e), which are the stable crystal surfaces. The SEM images were taken with the x axis aligned in the a-plane ([11-20]) direction of the sapphire substrate on which GaN was grown. It is known that the as grown GaN m-plane ([10-10]) crystal orientation lines up with the underlying sapphire a-plane ([11-20]) direction [16]. The x and y axes in the top view SEM image are therefore respectively in the m-plane ([10-10]) and a-plane X 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See standards/publications/rights/index.html for more information.

2 952 JOURNAL OF DISPLAY TECHNOLOGY, VOL. 12, NO. 9, SEPTEMBER 2016 Fig. 1. (a) Mircrorod LED fabrication process. (b), (c) The top and tilted views of the ICP-RIE etched n-gan microrod. (d) {11-20} hexagon microrods after a brief n-gan regrowth period. Small {10-10} facets were formed at some vertices, as indicated by red arrows. (e) Tiled view showing the {11-20} sidewalls and {11-22} inclined surface. The dashed blue lines depict the sidewall facets, including the small emerging {10-10} facet. (f), (g) Top and tilted views of the finished microrod LED. {10-10} define the final microrod orientation at the end of regrowth. ([11-20]) directions of GaN. The crystal orientation was confirmed by electron diffraction as will be described shortly. The top-view image in Fig. 1(d) shows the formation of {11-20} (a-plane) hexagonal sidewalls after a short period of regrowth. The tilted view image in Fig. 1(e) further shows inclined surfaces, which are nominally {11-22} surfaces [6], [17], [18]. These microrod vertical sidewalls and inclined surfaces are respectively nonpolar and semipolar planes, which have no and low polarization fields. A closer examination of Fig. 1(d) shows that additional crystal facets started to form at the hexagon corner regions indicated by the red pointers, which would otherwise be sharp vertices. This facet can be seen in the region encompassed by the red dashed rectangle in Fig. 1(e), where blue dotted lines are added for visual guidance. These small surfaces are in the [10-10] directions. Six pairs of InGaN well and GaN barrier MQWs were epitaxially grown by MOCVD on these microrod facets, ending with a final thin layer of p-gan. These InGaN/GaN layer structures were grown conformally on all facets. The top-view SEM image Fig. 1(f) shows the formation of {10-10} (a-plane) hexagonal sidewalls. Comparing the hexagons in Fig. 1(d) and (f), we see the particular rotation of the hexagons from the starting {11-20} to final {10-10} surfaces. The inclined surfaces also evolved from {11-22} to {10-11} planes. The rotation of the hexagons from Fig. 1(d) to (f) occurred because the {11-20} surfaces were outgrown by the emerging {10-10} surfaces during the course of MQW growth. This will be discussed in detail later. The microrod vertical sidewalls coalesced together after regrowth, as shown in the tilted view Fig. 1(g). The fine granular surface was due to the ITO Fig. 2. (a) Top-viewed SEM image of a multi-faceted microrod LED. (b) Scanned CL spectrum. (c) CL full spectrum image. {10-10} and {11-20} planes are respectively marked by a yellow contour and a red dashed contour for reference. (d), (i) Spectrally resolved CL images from 460 to 640 nm reveal the spectrally dependent emission patterns. coating. There are some larger pits on the top surface. Those are due to GaN pits because of the low growth temperature. The growth temperature of InGaN QWs was 805 C. III. RESULTS AND DISCUSSION The spatial luminescent property of the microrod LED was studied by cathodoluminescent (CL) measurement. The topview SEM image over a few microrods was first taken, as shown in Fig. 2(a). The CL spectrum and panchromatic image under e-beam excitation is respectively shown in Fig. 2(b) and (c). The {11-20} and {10-10} hexagons are respectively shown in red dashed and yellow solid lines for reference. The emission occurs outside the dark hexagons formed by the {11-20} planes. The dark hexagons correspond to the microrods after a brief GaN regrowth but before MQW growth, as shown in Fig. 1(d). This region has no QWs inside, therefore is dark on CL image. There is no CL emission from top c-plane QWs. It indicates that the c-plane QWs are highly defective, as also shown from the rough top surface in Fig. 1(g). The spectrally resolved CL images are shown in Fig. 2(c) (h). As noted previously, the microrod surfaces evolved from {11-20} to {10-10} planes. The regrown MQWs would therefore also follow the same surface evolution. The CL images at wavelength nm in Fig. 2(d) (e) show emission patterns from the starting {11-20} and/or {11-22} planes, as illustrated by the red dotted hexagon. The CL image at 520 nm [see Fig. 2(f)] is dim and could be viewed as a transition to the next emission pattern. The nm images in Fig. 2(g) (i) show hexagonal emission patterns from {10-10} and/or {10-11} planes, as illustrated by the yellow hexagon. These CL images showed that the emission wavelength of MQWs grown on the evolving micro rod facets changed along with the facet evolution.

3 LI et al.: MULTIFACET MICROROD LIGHT-EMITTING DIODE WITH FULL VISIBLE SPECTRUM EMISSION 953 Fig. 3. STEM images. (a) Cross section by FIB line m in Fig. 2(a) to show {11-20} QW structure. (b) Cross section by FIB line a in Fig. 2(a) to show {10-10} QW structure. (c) Enlarged {11-22} QW cross section image. (d) Enlarged {10-11} QW cross sec-tion image. (e) Enlarged {11-20} QW cross section image. (f) Enlarged {10-10} QW cross section image and the localized trench QWs. We used scanning transmission electron microscope (STEM) to examine the MQW structure. The sample was cleaved by a focused ion beam (FIB) along [10-10] and [11-20] to expose {11-20} and {10-10} MQW cross sections. The STEM cross sections at the locations labeled by the m and a lines in Fig. 2(a) are shown in Fig. 3(a) and (b), respectively. The crystal orientations were confirmed by electron diffraction patterns. The arrows in Fig. 3(a) were respectively identified as the {0002} c-plane, {11-22} semipolar, and {11-20} nonpolar plane directions. The arrows in Fig. 3(b) likewise were identified as the {0002} c-plane, {10-11} semipolar, and {10-10} nonpolar plane directions. The dark lines following the microrod profiles are InGaN MQWs. These lines provided snapshots of the growth evolution. Five pairs of pre-strain layers and six pairs of QWs were grown during the regrowth process. The c-plane MQWs, as shown in Fig. 3(a) and (b), do not have clear wellbarrier interfaces except for the first one or two layers. The rough interfaces with many V-pits were caused by high indium incorporation exceeding the alloy limitation [19]. The lack of CL emission from c-plane was due to this poor QW quality. The enlarged cross sections of the inclined {11-22} and {10-11} QWs are respectively shown in Fig. 3(c) and (d). {11-20} and {10-10} QWs are likewise shown in Fig. 3(e) and (f). The {11-22} and {11-20} ({11-2x}) QWs have larger spacing than {10-11} and {10-10} ({10-1x}) QWs, e.g. {11-20} QW spacing of 12 nm versus {10-10} QW spacing of 5 nm. This indicates that {11-2x} planes have a faster growth rate than {10-1x} planes. Localized high In content QWs were also found in the trench center, as shown by the enclosed dotted-line ellipse in Fig. 3(f). The hexagon orientation of {11-2x} and {10-1x} QWs respectively match well to the observed hexagon orientations in CL Fig. 2(d) (e) and Fig. 2(g) (h). They therefore are respectively the sources contributing to the observed nm and nm CL emission wavelength ranges. This also implies that {11-2x} QWs had lower indium content than {10-1x} QWs in this microrod structure [20]. The multi-facet microrod and planar c-reference samples were fabricated into LED chips by the standard LED fabrication processes. ITO thin film was sputtered on the top p-gan surface as a conductive layer to improve current spreading for electrical injection. Dry etching was performed to define a 300 by 300 μm chip area and expose a small n-gan region for n- contact. Cr/Ti/Au metals were deposited on the ITO layer and exposed n-gan for p- and n-contacts. The CIE chromaticity coordinates and optical microscope images are shown in Fig. 4(a). The correlated color temperatures are in the range from 1687 K to 4613 K for 50 ma to 300 ma. The electroluminescent (EL) spectra at various injection currents up to 300 ma are shown in Fig. 4(b). As current increases, a broad emission starts at 630 nm followed by the emergence of another emission at 500 nm. The emission color changes from dim red to orange yellow to bright white, showing dim warm to bright white color characteristic. The 500 nm and 630 nm emissions match to the observed CL ranges at nm [see Fig. 2(c) (d)] and nm [see Fig. 2(f) (g)]. The two peaks are thus respectively attributed to QWs grown on {11-2x} and {10-1x} planes. The EL spectra of the planar c-reference is shown in Fig. 4(c) for comparison. The emission occurs at much shorter wavelength region, as compared with the microrod LED case. This demonstrates the better In incorporation rate for MQWs grown on microrod LED. The 450 nm EL peak in the planar reference sample is due to the pre-strain super lattice InGaN/GaN layer for growth strain management. The light-output and the electrical performance are shown in Fig. 4(d). The I-V curve shows a turn-on voltage at 2.25 V. Above the turn-on voltage, the light output intensity increases up to 300 μw as current increases to 300 ma, while the driving voltage continue to increase to 6 V. This indicates current leakage. The low output power and leakage current could be due to the defective MQWs on the microrod c-plane top surface, as shown in the TEM study. This problem can be improved by capping the c-plane surface of micro rod by an oxide layer to prevent the defective MQW growth. The full visible spectrum emission covering over 200 nm spectral width from 460 to 660 nm is in particular useful because it can potentially provide a direct white light illumination without the need to use phosphor down conversion. The warm to white color shift along with optical power increase as current increases also suits well to the often desired dim warm color to bright white color illumination scheme in practice. The high resolution EL photographs of the microrod LED were taken by a 100 objective lens to investigate the spatial EL characteristics [see Fig. 4(e) (f)]. The enlarged images are

4 954 JOURNAL OF DISPLAY TECHNOLOGY, VOL. 12, NO. 9, SEPTEMBER 2016 Fig. 5. Growth evolution of microrod LED. (a), (b) The fast growing {11-20} planes are first grown on microrod, forming {11-20} hexagon. (c) The slow growing {10-10} planes start to from at the vertices. (d) QW growth. {11-20} planes grow fast and diminish laterally. {10-10} planes grow slowly and become larger. (e) The growth is finally limited by the {10-10} growth, resulting in {10-10} hexagon. EL region coincides with QWs grown in {10-10} growth region. Fig. 4. (a) CIE diagram of microrod LED as injection current increases from 10 to 300 ma. The insets show the EL images. (b) EL spectra of microrod LED span 200 nm spectral width. (c) EL spectra of the planar reference. (d) Light-current-voltage (L-I-V) show microrod LED turn on at 2.25 V. (e), (f) The high resolution EL images at 30 and 300 ma, showing organized EL spots between two adjacent microrods. shown in the inset. The dark circles correspond to the microrod top surfaces, which do not emit light as in the CL case. The EL surprisingly comes from an array of spots. The corresponding locations are illustrated by the red circles in SEM Fig. 2(a). This spotty EL pattern remained as the emission color shifted from red to yellow-green when current increased from 0 to 300 ma. This is somehow different from the above CL results where different emission wavelengths occur at different locations. EL measurement nevertheless is the ultimate indication for the electrical-driving of QWs. The spotty EL pattern, rather than the hexagon-line pattern, indicates that only QWs at the spot regions can be driven by electrical injection. QWs are either defective or lack of proper electron-hole injection at the three-boundary coalescent regions as illustrated by the blue circle in Fig. 2(a). The EL spots are likely related to the evolution from {11-20} to {10-10} hexagons [see Fig. 1(d) and (f)] during the microrod growth. Fig. 5(a) (f) depicts the growth evolution of multifaceted microrod LEDs. The {11-20} plane is known to grow faster than {10-10} [21]. This was also confirmed by comparing the {11-20} and {10-10} QW spacing between Fig. 3(e) and (f), where {11-20} QWs have significantly larger spacing than {10-10} QWs. The {11-20} hexagons are first formed on the cylindrical microrods during n-gan regrowth because {11-20} has a fast growth speed [see Figs. 5(a) (b)]. The slow-growth {10-10} facets start to grow at the vertices [see Fig. 5(c)]. The {11-20} planes have larger growth steps than the {10-10} planes in the subsequent QW and p-gan growth [see Fig. 5(d) (e)]. As a result, the {11-20} planes diminish and the {10-10} planes become wider. The {10-10} planes finally take over the {11-20} planes, resulting in the final {10-10} hexagons. This growth evolution is also applicable to the inclined {11-22} and {10-11} planes. The observed EL emission spot location is depicted by the dashed circle in Fig. 5(e). It covers {10-1x} and part of the nearby {11-2x} planes. We remark that the EL spots are formed as follows. The injected current flows to the {10-1x} MQWs first because the bandgap is lower around 630 nm emission region. As current increases, the injected current starts to overflow to the adjacent {11-2x} MQWs which has higher bandgap around 500 nm emission. This results in the emergence of the 500 nm emission. IV. CONCLUSION In conclusion, we have demonstrated a full visible spectrum emission from a 3D multi-faceted microrod LED and

5 LI et al.: MULTIFACET MICROROD LIGHT-EMITTING DIODE WITH FULL VISIBLE SPECTRUM EMISSION 955 observed an organized self-assembled EL emission spot pattern. CL study showed crystal plane dependent QW emission wavelength, which could be attributed to the different In incorporation. STEM study showed conformal growth of MQWs on micro rod facets. The evolution of the microrod shape from starting {11-20} to ending {10-10} hexagons during the growth is attributed to the growth competition between the fast growing {11-20} planes and the slow growing {10-10} planes. This crystal plane evolution resulted in the organized EL spot emission pattern. The full visible emission spectrum of this multi-faceted microrod LED and the understanding of the growth evolution leading to the spotty emission pattern could be useful in the development of next generation lighting and display applications. [17] T. Kim et al., Highly efficient yellow photoluminescence from {11 22} InGaN multiquantum-well grown on nanoscale pyramid structure, Appl. Phys. Lett., vol. 97, Dec. 2010, Art. no [18] C. Liu et al., Light emission from InGaN quantum wells grown on the facets of closely spaced GaN nano-pyramids formed by nano-imprinting, Appl. Phys. Express, vol. 2, Dec. 2009, Art. no [19] D. Holec, P. Costa, M. Kappers, and C. Humphreys, Critical thickness calculations for InGaN/GaN, J. Cryst. Growth, vol. 303, pp , May [20] R. Bhat and G. M. Guryanov, Experimental study of the orientation dependence of indium incorporation in GaInN, J. Cryst. Growth, vol. 433, pp. 7 12, Jan [21] B. Leung, Q. Sun, C. D. Yerino, J. Han, and M. E. Coltrin, Using the kinetic wulff plot to design and control nonpolar and semipolar GaN heteroepitaxy, Semicond. Sci. Technol., vol. 27, Jan. 2012, Art. no ACKNOWLEDGMENT The authors would like to thank Dr. T. C. Hsu and M. H. Shieh of Epistar Corporation and the Industrial Research Institute Taiwan for their technical support. REFERENCES [1] F. Qian, S. Gradecak, Y. Li, C.-Y. Wen, and C. M. Lieber, Core/Multishell nanowire heterostructures as multicolor, high-efficiency light-emitting diodes, Nano Lett., vol. 5, no. 11, pp , Sep [2] M. Funato et al., Monolithic polychromatic light-emitting diodes based on InGaN microfacet quantum wells toward tailor-made solid-state lighting, Appl. Phys. Express, vol. 1, no. 1, Jan. 2008, Art. no [3] Y. J. Hong et al., Visible-color-tunable light-emitting diodes, Adv. Mater., vol. 23, no. 29, pp , Jun [4] L. J. Lauhon, M. S. Gudiksen, D. Wang, and C. M. Lieber, Epitaxial core shell and core multishell nanowire heterostructures, Nature, vol. 420, pp , Nov [5] H. Sekiguchi, K. Kishino, and A. Kikuchi, Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate, Appl. Phys. Lett., vol. 96, Jun. 2010, Art. no [6] Y. 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Phys., vol. 76, Oct. 2013, Art. no Yun-Jing Li was born in Taipei, Taiwan, in She received the B.S. degree in resources engineering from National Cheng Kung University, Tainan, Taiwan, in 2008, and the M.S. degree in lighting and energy photonics from National Chiao Tung University (NCTU), Hsinchu, Taiwan, in 2011, where she is currently working toward the Ph.D. degree at the Institute of Electronics Engineering. Her current research interest includes GaN-based optoelectronics. Jet-Rung Chang received the B.S. degree in materials science and engineering, and the Ph.D. degree in electronics engineering from National Chiao Tung University, Hsinchu, Taiwan, in 2005 and 2013, respectively. He was involved in research on III V semiconductor materials for LEDs and HEMTs. He is currently with the Taiwan Semiconductor Manufacturing Company. His current research interest includes epitaxial growth and fabrication of SiGe semiconductor devices. Shih-Pang Chang received the B.S. degree in materials science and engineering from National Dong Hwa University, Hualien, Taiwan, in 2004, the M.S. degree in electrical engineering from National Central University, Taoyuan, Taiwan, in 2006, and the Ph.D. degree in electrooptical engineering from National Chiao Tung University, Hsinchu, Taiwan, in He is currently with National Nano Device Laboratories. His current research interests include epitaxial growth of various III-nitride materials, and fabrication of III V optoelectronic devices. Bo-Wen Lin received the B.S. and M.S. degrees in applied physics from Tunghai University, Taichung, Taiwan, in 2002 and 2004, respectively, and the Ph.D. degree in materials science and engineering from National Chiao Tung University, Hsinchu, Taiwan, in His current research interests include epitaxial growth of various III-nitride materials, and fabrication of III V optoelectronic devices.

6 956 JOURNAL OF DISPLAY TECHNOLOGY, VOL. 12, NO. 9, SEPTEMBER 2016 Yen-Hsien Yeh received the B.S. degree in electronic engineering and physics from the Fu Jen Catholic University, Taipei, Taiwan, in 2001, the M.S. degree in physics from National Tsing Hua University, Hsinchu, Taiwan, in 2003, and the Ph.D. degree in electrophysics from National Chiao Tung University, Hsinchu, in Since February 2014, he has been a Postdoctoral Research Associate at the Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan. His current research interests include the fabrication of optoelectronic devices and the development of green energy technologies. Hao-Chung Kuo (M 98 SM 06 F 14) received the B.S. degree in physics from National Taiwan University, Taipei, Taiwan, the M.S. degree in electrical and computer engineering from Rutgers University, New Brunswick, NJ, USA, in 1995, and the Ph.D. degree from the Electrical and Computer Engineering Department, University of Illinois at Urbana Champaign, Urbana, IL, USA, in He has an extensive professional career both in research and industrial research institutions as a Research Assistant with the Lucent Technologies, Bell Laboratories, Murray Hill, NJ, from 1993 to 1995, and a Senior R&D Engineer with the Fiber-Optics Division, Agilent Technologies, Santa Clara, CA, from 1999 to 2001, and LuxNet Corporation, Fremont, CA, from 2001 to Since October 2002, he has been at the Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan, as a Faculty Member. His current research interests include semiconductor lasers, verticalcavity surface-emitting lasers, blue and ultraviolet light-emitting diode lasers, quantum-confined optoelectronic structures, optoelectronic materials, and solar cells. Yuh-Jen Cheng received the M.S. degree in optics from the University of Rochester, Rochester, NY, USA, in 1990, and the Ph.D. degree in applied physics from Stanford University, Stanford, CA, USA, in He is currently an Associate Research Fellow at the Research Center for Applied Sciences, Academia Sinica, Taiwan. His research interests include IIInitride-based optoelectronics, material growth, and devices for green energy applications. Chun-Yen Chang (S 69 M 70 SM 81 F 88 LF 05) was born in Feng-Shan, Taiwan. He received the B.S. degree in electrical engineering from National Cheng Kung University (NCKU), Tainan, Taiwan, in 1960, and the M.S. and Ph.D. degrees from National Chiao Tung University (NCTU), Hsinchu, Taiwan, in 1962 and 1969, respectively. He has profoundly contributed to the areas of microelectronics, microwave, and optoelectronics, including the invention of the method of low-pressure metal organic chemical vapor deposition using triethylgallium to fabricate lightemitting diodes, lasers, and microwave devices. He pioneered works on Zn incorporation in 1968, nitridation in 1984, and fluorine incorporation in SiO2 for ULSIs in 1984, as well as in the charge transfer in semiconductor oxide semiconductor system in 1968, carrier transport across metal semiconductor barriers in 1970, and the theory of metal semiconductor contact resistivity in In 1963, he joined NCTU as an Instructor, establishing a high-vacuum laboratory. In 1964, he and his colleagues established the nation s first and state-of-the-art Semiconductor Research Center, NCTU, with a facility for silicon planar device processing, where they made the nation s first Si planar transistor in April 1965 and, subsequently, the first IC and MOSFET in August 1966, which strongly forms the foundation of Taiwan s hi-tech development. From 1977 to 1987, he single handedly established a strong electrical engineering and computer science program at NCKU, where GaAs, α-si, and poly-si research was established in Taiwan for the first time. He consecutively served as the Dean of Research from 1987 to 1990, the Dean of Engineering from 1990 to 1994, and the Dean of Electrical Engineering and Computer Science from 1994 to Simultaneously, from 1990 to 1997, he served as the Founding President of the National Nano Device Laboratories, Hsinchu. Since August 1998, he has been the President of the Institute of Electronics, NCTU. In 2002, to establish a strong system design capability, he initiated the National Program of System on Chip, which is based on a strong Taiwanese semiconductor foundry. Dr. Chang was a member of the Academia Sinica in 1996 and a Foreign Associate of the National Academy of Engineering in He received the Third Millennium Medal in 2000, the Nikkei Asia Prize for the science category in Japan in 2007, and regarded as the Father of Taiwan s semiconductor industries.