Spectroscopic analysis and two-dimensional confocal photoluminescence properties of GaN films grown on silicon and sapphire substrates

Jeong Hyun 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.8

The spectroscopic analysis and two-dimensional confocal photoluminescence (PL) properties of GaN flms grown on silicon (Si) and sapphire (Al2O3) substrates were investigated. Due to crystal strain in GaN flms on various substrates, the prominent PL peaks of GaN on Si and Al2O3 substrates varied by 10 meV. A two-dimensional confocal laser scattering image of GaN on Si displays a surface crack generated by a large lattice mismatch between Si and GaN. Based on the two-dimensional PL intensity distribution of the near band edge and a yellow band of GaN flms, the PL characteristics of GaN on Si and Al2O3 substrates are mostly afected by crystal strain and crystalline defect, respectively. Furthermore, the PL intensity distribution of the GaN donor–acceptor pair (DAP) peak on Si represents a characteristic of the surface crack, while the GaN donor-bound exciton (D0 X) and DAP peaks on Al2O3 exhibit randomly distributed bright and dark spots without a pattern or singularity. It suggests that the PL properties of GaN on Si and Al2O3 substrates are predominantly afected by the crystal strain and crystalline defect of GaN, respectively. In addition, in contrast to the fat surface of the GaN flm on the Si substrate, the change in the D0 X PL peak position was clearly observed along the crack lines in the peak energy fltered two-dimensional confocal PL image.

Semiconductor–Insulator–Semiconductor Diode Consisting of Monolayer MoS₂, h-BN, and GaN Heterostructure

Jeong, Hyun,Bang, Seungho,Oh, Hye Min,Jeong, Hyeon Jun,An, Sung-Jin,Han, Gang Hee,Kim, Hyun,Kim, Ki Kang,Park, Jin Cheol,Lee, Young Hee,Lerondel, Gilles,Jeong, Mun Seok American Chemical Society 2015 ACS NANO Vol.9 No.10

<P>We propose a semiconductor–insulator–semiconductor (SIS) heterojunction diode consisting of monolayer (1-L) MoS<SUB>2</SUB>, hexagonal boron nitride (h-BN), and epitaxial p-GaN that can be applied to high-performance nanoscale optoelectronics. The layered materials of 1-L MoS<SUB>2</SUB> and h-BN, grown by chemical vapor deposition, were vertically stacked by a wet-transfer method on a p-GaN layer. The final structure was verified by confocal photoluminescence and Raman spectroscopy. Current–voltage (<I>I</I>–<I>V</I>) measurements were conducted to compare the device performance with that of a more classical p–n structure. In both structures (the p–n and SIS heterojunction diode), clear current-rectifying characteristics were observed. In particular, a current and threshold voltage were obtained for the SIS structure that was higher compared to that of the p–n structure. This indicated that tunneling is the predominant carrier transport mechanism. In addition, the photoresponse of the SIS structure induced by the illumination of visible light was observed by photocurrent measurements.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-10/acsnano.5b04233/production/images/medium/nn-2015-042335_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5b04233'>ACS Electronic Supporting Info</A></P>

Ultraviolet, blue, and green InGaN-based light-emitting diodes functionalized with ZnO nanorods

Jeong, Hyun,Salas-Montiel, Rafael,Lerondel, Gilles,Jeong, Mun Seok Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.708 No.-

<P><B>Abstract</B></P> <P>We investigated the augmentation in the light-output power of InGaN light-emitting diodes (LEDs) functionalized with ZnO nanorods (NRs) according to the emission wavelength of the LEDs and the volume fraction of the ZnO NRs. The ZnO NRs were fabricated on top of the ultraviolet, blue, and green InGaN LEDs using the hydrothermal method. The optical properties of the LEDs and ZnO NRs were examined by electroluminescence, photoluminescence, and Raman scattering at room temperature. The measurements of light-output power versus current and current as a function of voltage showed that there were considerably different enhancements in the light-output power of InGaN LEDs functionalized with ZnO NRs at different emission wavelengths of the LEDs, while no changes were observed in the electrical properties. Three-dimensional finite-difference time-domain simulations were conducted to support the experimental results. Both experimental and theoretical results indicated that the light-extraction efficiency of InGaN LEDs functionalized with ZnO NRs was significantly affected by the differences between the refractive indices of the GaN layers, indium–tin oxide layer, and ZnO NRs, which could be changed by the emission wavelength of the LEDs and volume fraction of the ZnO NRs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnO nanorods are functionalized on surface of UV, blue, and green LEDs. </LI> <LI> Light output power of LED is augmented by ZnO nanorods due to light waveguide. </LI> <LI> Light extraction efficiency is notably influenced by emission wavelength of LED. </LI> <LI> Volume fraction of ZnO nanorods is significant for light extraction efficiency. </LI> </UL> </P>

Metal–Insulator–Semiconductor Diode Consisting of Two-Dimensional Nanomaterials

Jeong, Hyun,Oh, Hye Min,Bang, Seungho,Jeong, Hyeon Jun,An, Sung-Jin,Han, Gang Hee,Kim, Hyun,Yun, Seok Joon,Kim, Ki Kang,Park, Jin Cheol,Lee, Young Hee,Lerondel, Gilles,Jeong, Mun Seok American Chemical Society 2016 NANO LETTERS Vol.16 No.3

<P>We present a novel metal-insulator-semiconductor (MIS) diode consisting of graphene, hexagonal BN, and monolayer MoS2 for application in ultrathin nano electronics. The MIS heterojunction structure was fabricated by vertically stacking layered materials using a simple wet chemical transfer method. The stacking of each layer was confirmed by confocal scanning Raman spectroscopy and device performance was evaluated using current versus voltage (I-V) and photocurrent measurements. We clearly observed better current rectification and much higher current flow in the MIS diode than in the p-n junction and the metal-semiconductor diodes made of layered materials. The I-V characteristic curve of the MIS diode indicates that current flows mainly across interfaces as a result of carrier tunneling. Moreover, we observed considerably high photocurrent from the MIS diode under visible light illumination.</P>

성금연류 가야금산조 조현법 연구 ― 1950년대 음원을 중심으로 ―

추정현 ( Chu¸ Jeong-hyun ) 전남대학교 호남학연구원 2020 호남학 Vol.0 No.68

본고에서는 1950년대에 발매된 성금연의 세 음원 King Star K5955, Oasis 5560, 킹스타 KSM-1085 진양조를 채보하여 조현법이 어떻게 변화되었는지 살펴보았다. 또 최초로 가야금산조 음원을 남긴 김해선과 성금연의 스승인 안기옥의 진양조 음원을 성금연의 King Star K5955 음원과 비교해 보았다. 이를 통해 성금연류 가야금산조의 변화양상을 살펴볼 수 있었는데, 그 내용은 다음과 같다. 첫째, 가야금의 ‘지’줄을 ‘B’음으로 조현하는 현재의 조현법과 달리 King Star K5955 음원에서는 단2도가 높은 ‘c’음에 맞춰 조현하였는데, 이러한 현상은 1920년대 유성기 음반에 전하는 김해선과 안기옥의 산조 음원, 1960년대 김윤덕의 산조 음원에서도 확인할 수 있었다. 둘째, 킹스타 KSM-1085 음원 중 진양조와 Oasis 5560 음원에서는 ‘지’줄을 ‘B’음과 ‘c’음 중간 높이의 음으로 조현하여 산조를 시작하였다. 이는 King Star K5955에 비해 ‘지’줄이 낮아진 것인데, 이렇게 조현하는 현상은 성금연이 연주한 가야금산조의 다양한 음원과 그 딸들의 음원에서도 나타났다. 셋째, King Star K5955 음원과 Oasis 5560 음원에서는 13현 가야금으로 겹청조현법을 사용하였는데, 맨 아랫줄을 ‘흥’(G′)줄보다 한 옥타브 아래인 ‘청’(G″)줄로 조현함으로써 산조가야금으로 연주하는 것보다 음역이 확대되었다. 넷째, 성금연의 King Star K5955 음원에서는 평조로 진양조를 시작하였는데, 이는 성금연의 스승인 안기옥이 남긴 진양조 음원이 평조로 시작하는 것과 동일하다. 또 성금연과 안기옥의 평조는 최초로 가야금산조 음원을 남긴 김해선의 평조와 조현법이 동일하고, 같은 선율을 연주하고 있어 성금연의 King Star K5955 음원이 초기 가야금산조의 모습을 담고 있음을 확인할 수 있었다. 오늘날의 조현법보다 ‘지’줄을 단2도 높게 조현했던 성금연이 후에 ‘지’줄을 낮게 맞춰가며 산조를 만들어간 현상은 음계에까지 변화를 주는, 말하자면 산조의 음악적인 구성 체계를 바꾸는 중요한 전환점이 되었다고 볼 수 있다. This study investigated how tuning methods had been changed by transcribing Jinyangjo of three recording sources: King Star K5955, Oasis 5560, and King Star KSM-1085 by Seong Geum-yeon released in the 1950s. In addition, this paper compared Jinyangjo of Kim Hae-seon, who left the Gayageum Sanjo recording for the first time, and Ahn Gi-ok, the teacher of Seong Geum-yeon, with the King Star K5955 by Seong Geum-yeon. Through this analysis, it was possible to examine the aspect of transition of Seong Geum-yeon Ryu Gayageum Sanjo. The results are as follows. First, unlike the current tuning method in which the Gayageum's ji string is tuned to the ‘B’ sound, the King Star K5955 recording was tuned to the ‘c’ sound as a minor second higher tone, and this method was also confirmed in the Gayageum Sanjo of Kim Hae-seon and Ahn Gi-ok in the 1920's gramophone records, and the Sanjo recording by Kim Yoon-deok in the 1960s. Second, Jinyangjo in King Star KSM-1085 and Oasis 5560 started Sanjo tuned with the ji string as sound in the middle of the ‘B’ and ‘c’. Compared with the King Star K5955, the ji string was lowered, and this method was also revealed in the various recording sources of Gayageum Sanjo played by Seong Geum-yeon and their daughters. Third, the Sanjo of the King Star K5955 and the Oasis 5560 used a double-cheong tuning method with 13-string Gayageum, which extended tone register, compared with the playing of Sanjo Gayageum, by tuning the bottom Heung (G′) string to an octave lower Cheong (G″) string. Forth, in Seong Geum-yeon's King Star K5955 recording, Jinyangjo was started with Pyeongjo, which is the same as the Jinyangjo left by Ahn Gi-ok, Seong's teacher. In addition, the tuning method of Pyeongjo by Seong Geum-yeon and Ahn Gi-ok was the same as that of Kim Hae-seon, who left the first Gayageum Sanjo recording, and they played all the identical melody. Therefore, it was confirmed that the recording source of Seong Geum-yeon's King Star K5955 contained the shape of the early Gayageum Sanjo. The fact that Seong Geum-yeon tuned the ji string as a minor second higher sound than today's tuning method and later composed the Sanjo by adjusting the ji string lower might have been an important turning point in changing the scale, namely musical composition system of Sanjo.

외교총장 육징상(陸徵祥)의 베네딕도 수도회 수행과 구국 활동 - 육징상(陸徵祥) 회고록 『回憶與隨想』을 중심으로

김정현 ( Kim¸ Jeong Hyun ) 중국사학회 2022 中國史硏究 Vol.- No.136

Lu Zhengxiang (陸徵祥, 1871-1949) is the only person in Chinese history to make a life vow at the Benedictine Abbey Saint-Andrew's in Bruges, Belgium, after serving as foreign minister and prime minister of the Republic of China as a diplomat in the late Qing Dynasty. He is a former prime minister and a priest. During his tenure as Minister of Foreign Affairs of the Republic of China, he established a system for cultivating diplomatic talents and laid the foundation for the modernization of Chinese diplomacy. Under the coercion of President Yuan Shikai, Lu signed the Treaty of 21 Treaties with Japan which the people criticized, but his decision to refuse to sign the Treaty of Versailles at the Paris Peace Conference in 1919 restored honor for his mistake in signing the 21 Treaties. The reasoning behind Lu Zhengxiang leaving the office was not just to leave the world; he did other rescue activities in the monastery. He entered the Monastery of St. Andreas, Belgium, on the 5th of July 1927 and performed the asceticism of poverty. Lu’s motivation for choosing the Benedictine Monastery was to realize the revival of the Chinese nation by absorbing the Catholic spirit, the spiritual power of Europe. He helped the Catholic Church in China while paying attention to China's political, social, and ecclesiastical developments at the monastery. During the Sino-Japanese War, he gave a lecture in Belgium to criticize the war of aggression of Japan and the Nazis. He informed China's efforts to resist the war and the situation of the Catholic Church. He was in charge of the < 益世報 Overseas Correspondence >, and carried out rescue activities to promote and help China's anti-Japanese war internationally by mobilizing all his contacts as a diplomat and linking with Catholic organizations. Lu’s rescue activities were a Catholic practice of love and loyalty to the country as a priest. His theory of reforming and supplementing Chinese culture as a part of Catholic religious culture overestimates moral competence. Further, the idea is criticized for its' limitation on national salvation through cultural convergence without a realistic basis. However, his salvation ideology and practice are included in the large flow of rescue activities attempted by Chinese intellectuals in the first half of the 20th century. It is meaningful in that it enhances China's international status by acting as a bridge between the Chinese government, the Vatican, the Chinese Catholic Church, and attempts to converge East and West cultures.

The Interplanetary Dust Cloud Revealed by AKARI IRC All-Sky Survey Observations

Jeonghyun Pyo,Seung Soo Hong,Suk Minn Kwon,Munetaka Ueno,Masateru Ishiguro,Fumihiko Usui,Takafumi Ootsubo,Daisuke Ishihara,Tadashi Mukai,AKARI IRC Team 한국천문학회 2009 天文學會報 Vol.34 No.1

A Report on the Reduction of AKARI IRC All-Sky Survey Data for Zodiacal Emission

Jeonghyun Pyo,M. Ishiguro,M. Ueno,D. Ishihara,F. Usui,S. S. Hong,AKARI IRC Team 한국천문학회 2007 天文學會報 Vol.32 No.1

Therapeutic Hypothermia Improves Post Resuscitation Myocardial Function in a Rat Model of Myocardial Infarction

Jeonghyun Park 대한체질인류학회 2011 대한체질인류학회 학술대회 연제 초록 Vol.54 No.-

MicroRNA-mediated Regulation of the Development and Functions of Follicular Helper T cells

Jeonghyun Lee,Hyosung Park,Jiyoung Eom,Seung Goo Kang 대한면역학회 2018 Immune Network Vol.18 No.2