MEE법으로 성장한 InAs/GaAs 양자점의 발광특성

오재원,변혜령,류미이,송진동,Oh, Jae Won,Byun, Hye Ryoung,Ryu, Mee-Yi,Song, Jin Dong 한국진공학회 2013 Applied Science and Convergence Technology Vol.22 No.2

Migration-enhanced epitaxy 성장한 InAs/GaAs 양자점(quantum dots)의 광학적 특성을 PL (photoluminescence)과 Time-resolved PL 이용하여 분석하였다. InAs 양자점은 In을 9.3초 공급하고 5초 차단한 후 As을 3초, 4초, 6초, 또는 9초 공급하고 5초 차단하는 과정을 3회 반복하여 성장하였다. As을 3초 공급한 시료의 PL 피크는 1,140 nm에서 나타나고, PL 세기는 다른 세 시료에 비해 매우 약하게 나타났다. As 공급시간을 3초에서 증가하였을 때 모든 PL 피크는 1,118 nm로 청색이동하여 나타났으며, PL 세기는 증가하였다. As을 6초 공급한 시료의 PL 세기가 가장 강하게 나타나고, 반치폭(full width at half maximum)도 가장 좁게 나타났다. 이러한 결과는 양자점의 밀도와 균일도(크기변화)로 설명된다. 또한 발광파장에 따른 PL 소멸시간은 PL 피크 근처에서 가장 길게 나타났다. The luminescence properties of InAs/GaAs quantum dots (QDs) grown by a migration enhanced epitaxy method have been investigated by using photoluminescence (PL) and time-resolved PL measurements. The MEE method supplies materials in a series of alternate depositions with migration enhancing time between each deposition. After In source was supplied for 9.3 s, the growth was interrupted for 5 s. Subsequently, As source was open for 3 (AT3), 4(AT4), 6 (AT6), or 9 s (AT9), and the growth was interrupted for 5 s again. This growth sequence was repeated 3 times for the growth of InAs QDs. The PL peak of the AT3 was 1,140 nm and the PL intensity was very weak compared with that of the other three samples. The PL peak of all samples except the AT3 sample was 1,118 nm, which is blueshifted from 1,140 nm, and the PL intensity was increased compared to that of the AT3. These results can be explained by the increased QD density and the improved QD uniformity. The AT6 sample showed the strongest PL intensity and the narrowest full width at half maximum. The PL decay time of AT6 increased with increasing emission wavelength from 940 to 1,126 nm, reaching a maximum decay time of 1.09 ns at 1,126 nm, and then decreased as the emission wavelength was increased further.

Ferromagnetic Properties of Nickel-Implanted Al0.35Ga0.65N

Mee-Yi Ryu,Jeremy Raley,Pan Wu,Robert Hengehold,Yicheng Lu,Yung Kee Yeo 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.5

Magnetic characterization studies of Ni-implanted Al$_{0.35}$Ga$_{0.65}$N have been made for various magnetic fields and sample temperatures by using a superconducting quantum interference device (SQUID). Ni ions were implanted at 200 keV to a dose of 3 $\times$ 10$^{16}$ cm$^{-2}$ at room temperature. The material was found to show clear signs of ferromagnetism after annealing between 675 and 775 $^\circ$C for 5 min. The ferromagnetic property persisted above room temperature, and a coercive field width of 118 Oe and a remanent field of 16 \% of the saturation magnetization of 2.6 $\times$ 10$^{-5}$ emu were obtained at 300 K after annealing at an optimum annealing temperature of around 750 $^\circ$C. This ferromagnetic property was also confirmed with field-cooled and zero-field-cooled magnetization measurements, and the Curie temperature was estimated to be around 350 K. Cathodoluminescence and X-ray diffraction (XRD) measurements showed that the significant implantation-related damage was recovered after annealing at 750 $^\circ$C, indicating a good Ni incorporation in the Al$_{0.35}$Ga$_{0.65}$N. Furthermore, the XRD measurements also showed no indication of secondary phase formation or Ni clusters, which implies that we had observed a dilute ferromagnetic semiconductor behavior.

Optical Investigation of Quaternary AlxInyGa1-x-yN Epilayers Grown by Using Pulsed Metalorganic Chemical Vapor Deposition

Mee-Yi Ryu,C. Q. Chen,J. H. Song,M. Asif Khan 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I

Photoluminescence (PL) and time-resolved PL measurements have been carried out in the quaternary AlxInyGa1.x.yN epilayers grown by using pulsed metalorganic chemical vapor deposition (PMOCVD). PMOCVD-grown AlInGaN layers show a strong blueshift and linewidth broadening of the emission band with excitation power density, and the PL decay time increases with decreasing emission energy. These results are characteristic of localized carrier/exciton recombination, which is beneficial for strong spontaneous emission for ultraviolet (UV) light-emitting diodes (LEDs). The obtained properties indicate that quaternary AlInGaN is a promising material for UV applications and especially that the PMOCVD process is a useful method for fabricating the active region of a deep UV LED.:10chh9

Electrical activation studies of Si-implanted AlxG1?xN as a function of ion dose, anneal temperature, and anneal time

Mee-Yi Ryu,E. A. Moore,R. L. Hengehold,T. D. Steiner,Y. K. Yeo 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3

Electrical activation studies of Si-implanted AlxG1ကxN grown on sapphire substrate have been made as a function of ion dose, anneal temperature, and anneal time. The samples were annealed from 1200 to 1350 C with a 500 A thick AlN cap in a nitrogen environment. The optimum anneal temperature for Al0:25Ga0:75N samples implanted with a dose of 1 1015 cmက2 is around 1350 C, exhibiting nearly 87 % electrical activation eciency. Both the electrical activation eciency and Hall mobility of Si-implanted Al0:18Ga0:82N annealed at 1200 C from 5 to 25 min increase continuously with anneal time, but at a much slower rate as anneal time increases. The activation eciencies of 94 and 89 % were obtained for doses of 1 1015 and 5 1014 cmက2, respectively, after annealing at 1200 C for 25 min, which are the highest activation eciency reported for a given dose, to the best of our knowledge.

Effect of Growth Cycles on the Luminescence Properties of InP/InGaP Quantum Structures Grown Using Migration-Enhanced Epitaxy

Il-Wook Cho,Mee-Yi Ryu,Jin Dong Song 한국진공학회(ASCT) 2019 Applied Science and Convergence Technology Vol.28 No.5

The luminescence properties of InP/InGaP quantum structures (QSs) grown using migration-enhanced epitaxy (MEE) with different numbers of repetition of the growth cycles are investigated using temperature-dependent photoluminescence (PL) and time-resolved PL. As the number of MEE repetition cycles increases from 3 to 8, the main PL peak originating from quantum dashes (QDashes) is red-shifted from 1.74 to 1.59 eV, owing to the change in the aspect-ratio of InP QDashes, whereas the PL peak energy originating from InP quantum dots and InGaP wetting layer remains nearly constant. The sample grown with six MEE repetition cycles shows the strongest integrated PL intensity with a comparatively narrow linewidth at room temperature. The six-cycled sample demonstrates an increase in PL decay time and radiative lifetime up to the highest temperature (120 K). These results indicate that the structural and luminescence properties of the InP/InGaP QSs can be controlled by adjusting the number of MEE repetition cycles; the best optical properties are obtained with the six-cycled InP/InGaP QSs sample at a growth temperature of 480 ℃.

Optical Properties of InP/InGaP Quantum Structures Grown by a Migration Enhanced Epitaxy with Different Growth Cycles

Oh, Jae Won,Cho, Il-Wook,Ryu, Mee-Yi,Song, Jin Dong The Korean Vacuum Society 2015 Applied Science and Convergence Technology Vol.24 No.3

InP/InGaP quantum structures (QSs) were grown on GaAs (001) substrates by a migration-enhanced molecular beam epitaxy method. Temperature-dependent photoluminescence (PL) and emission wavelength-dependent time-resolved PL (TRPL) were performed to investigate the optical properties of InP/InGaP QSs as a function of migration enhanced epitaxy (MEE) growth cycles from 2 to 8. One cycle for the growth of InP QS consists of 2-s In and 2-s P supply with an interruption time of 10 s after each source supply. As the MEE growth cycle increases from 2 to 8, the PL peak is redshifted and exhibited different (larger, comparable, or smaller) bandgap shrinkages with increasing temperature compared to that of bulk InP. The PL decay becomes faster with increasing MEE cycles while the PL decay time increases with increasing emission wavelength. These PL and TRPL results are attributed to the different QS density and size/shape caused by the MEE repetition cycles. Therefore, the size and density of InP QSs can be controlled by changing the MEE growth cycles.

Height of elevated fetal buttock for prediction of successful external cephalic version

( Jun Yi Lee ),( Yeorae Kim ),( In Sook Sohn ),( You Jung Han ),( Jin Hoon Chung ),( Moon Young Kim ),( Min Hyoung Kim ),( Hyun-mee Ryu ),( Sunghong Joo ),( Jung Yeol Han ) 대한산부인과학회 2020 Obstetrics & Gynecology Science Vol.63 No.1

Objective To increase the rate of successful external cephalic version (ECV) and to minimize the complications, it is important to identify the predictors of success. Therefore, the purpose of this study was to investigate whether the height of the elevated fetal buttock (HOB) is a valuable predictor of successful ECV or not. Methods This prospective study was conducted from August 2016 to June 2018. A total of 139 pregnant women with breech presentation were enrolled in the study. HOB from the maternal pubic symphysis was measured on ultrasonography. The predictability and cut-off value of HOB for successful ECV were evaluated. Results Among the 139 patients, 114 (82%) had successful ECV. The adjusted odds ratio for multiparity, amniotic fluid index (AFI) >14 cm, and HOB >7.8 cm were 10.80 (95% confidence interval [CI], 1.57-74.94), 5.26 (95% CI, 1.06-26.19), and 10.50 (95% CI, 1.03-107.12), respectively. Areas under the curve (AUCs) for AFI, HOB, and parity were 0.66 (95% CI, 0.54-0.78), 0.74 (95% CI, 0.64-0.85), and 0.69 (95% CI, 0.62-0.76), respectively. HOB had the largest AUC, but there were no significant differences among the AUCs of other factors. The cut-off value of HOB was 6 cm. Conclusion This study showed that the AUC of HOB was greater than that of parity and AFI, although it was not statistically significant. As HOB is a noninvasive and comprehensive marker to predict successful ECV, consideration of HOB would be helpful before conducting ECV. Further studies are needed.

Three cases of rare SRY-negative 46,XX testicular disorder of sexual development with complete masculinization and a review of the literature

Bom Yi Lee,Shin Young Lee,Yeon Woo Lee,Shin Young Kim,Jin Woo Kim,Hyun Mee Ryu,Joong Shik Lee,So Yeon Park,Ju Tae Seo 대한의학유전학회 2016 대한의학유전학회지 Vol.13 No.2

Purpose: To identify the clinical characteristics of SRY-negative male patients and genes related to male sex reversal, we performed a retrospective study using cases of 46,XX testicular disorders of sex development with a review of the literature. Materials and Methods: SRY-negative cases of 46,XX testicular disorders of sex development referred for cytogenetic analysis from 1983 to 2013 were examined using clinical findings, seminal analyses, basal hormone profiles, conventional cytogenetic analysis and polymerase chain reaction. Results: Chromosome analysis of cultured peripheral blood cells of 8,386 individuals found 19 cases (0.23%) with 46,XX testicular disorders of sex development. The SRY gene was confirmed to be absent in three of these 19 cases (15.8%). Conclusion: We report three rare cases of SRY-negative 46,XX testicular disorders of sex development. Genes on autosomes and the X chromosome that may have a role in sex determination were deduced through a literature review. These genes, through differences in gene dosage variation, may have a role in sex reversal in the absence of SRY.

An unusual de novo duplication 10p/deletion 10q syndrome

Bom-Yi Lee,Ju-Yeon Park,Yeon-Woo Lee,Ah-Rum Oh,Shin-Young Lee,Eun-Young Choi,Moon-Young Kim,Hyun-Mee Ryu,So-Yeon Park 대한의학유전학회 2015 대한의학유전학회지 Vol.12 No.1

We herein report an analysis of a female baby with a de novo dup(10p)/del(10q) chromosomal aberration. A prenatal cytogenetic analysis was performed owing to abnormal ultrasound findings including a choroid plexus cyst, prominent cisterna magna, and a slightly medially displaced stomach. The fetal karyotype showed additional material attached to the terminal region of chromosome 10q. Parental karyotypes were both normal. At birth, the baby showed hypotonia, upslanting palpebral fissures, a nodular back mass, respiratory distress, neonatal jaundice and a suspicious polycystic kidney. We ascertained that the karyotype of the baby was 46,XX,der(10)(pter→q26.3::p11.2→pter) by cytogenetic and molecular cytogenetic analyses including high resolution GTG-and RBG-banding, fluorescence in situ hybridization, comparative genomic hybridization, and short tandem repeat marker analyses. While almost all reported cases of 10p duplication originated from one of the parents with a pericentric inversion, our case is extraordinarily rare as the de novo dup(10p)/ del(10q) presumably originated from a rearrangement at the premeiotic stage of the parental germ cell or from parental germline mosaicism.

Prenatally Diagnosed Uncommon Mosaic Autosomal Trisomy

Bom-Yi Lee,So-Yeon Park,Moon-Hee Lee,Jin-Woo Kim,Ju-Yeon Park,Eun-Young Choi,Yeon-Woo Lee,Ah-Rum Oh,Shin-Young Lee,Min-Hyung Kim,Hyun-Mee Ryu 대한의학유전학회 2009 대한의학유전학회지 Vol.6 No.1

Prenatal diagnosis of rare autosome mosaicism involvingchromosomes other than chromosome 13, 18, 21 or the sex chromosome is encountered prognostic dilemma during genetic counseling. We report four cases of level Ⅲ uncommon mosaicism of trisomy 5, 16 and 20,diagnosed prenatally. In case 1 with mosaic trisomy 20, there was a higher mosaic ratio of trisomy 20 in the repeat amniocentesis (62.1%) than in the first (36.6%) with normal fetal ultrasound finding except for a relatively small aorta on a 3-vessel view of the fetal heart. Case 2 showed a low rate of mosaic trisomy 20 (5.25%) in cultured amniocytes but normal karyotype in the repeat amniocentesis, who delivered a normal healthy baby. Case 3 showed a 13.6% of trisomy 16 mosaicism in the 30 cells of cultured amniocytes. Sixty cells from a fetal blood sample at termination showed non-mosaic 46,XX normal karyotype, while skin fibroblasts had 22.5% trisomy 16 in 40 metaphases. The autopsy showed ventricular septal defect (VSD). Case 4 with low grade mosaicism (10.5%) of trisomy 5 resulted in elective termination, though the ultrasoumd showed growsly normal fetus. Although level Ⅲ mosaicism is regarded as true mosaicism, it is difficult to predict the outcome of the fetus with rare mosaic autosome trisomy. Therefore mosaic autosome trisomy of fetus should be carefully interpreted with more various approaches including repeat sampling and targeted fetal ultrasound. 산전에서 성염색체와 13번, 18번, 21번 염색체를 제외한상 염색체의 모자이시즘은 발생빈도가 낮고 증례보고가 적어서 예후 예측이 어렵다. 저자들은 삼염색체성 5번, 16번, 20번의 산전진단 4례를 보고하고자 한다. 모자잌 삼염색체성 20번 2례 중 증례 1은 양수 염색체 검사에서 36.6%의 모자이시즘을 보였으나 재검한 양수 검사에서는 보다 높은 빈도 (62.1%)를 보였다. 증례 2에서는 양수 염색체 검사에서 모자이시즘 삼염색체성 20번이 5.25% 였으나, 재검 양수천자결과는 정상 핵형을 보였다. 증례 3은 30개의 양수세포에서 삼염색체성 16번의 모자이시즘이 13.6% 관찰되었다. 임신 종결 후, 총 60개의 태아 혈액 세포에서 모자이시즘 없는 정상 핵형이 관찰되었으나 태아의 피부 섬유아세포에서 얻은 40개의 중기상 세포에서는 22.5%의 삼염색체성 16번 모자이시즘을 보였다. 부검결과 심실중격결손(ventricular septal defect)이 관찰되었다. 증례 4는 76개의 중기상 세포에서 10.5%의 삼염색체성 5번 모자이시즘을 보였으나 태아의 초음파검사에서는 정상소견을 보였다. Level Ⅲ 모자이시즘은 진성 모자이시즘으로 간주되지만 발생빈도가 낮은 상염색체의 삼염색체성 모자이시즘은 태아의 예후를 예견하기 어려우므로 산전 진단시 여러 조직의 재검 및 태아 초음파 소견과 함께 다양한 임상적 접근 방법으로 그 해석에 신중을 기해야 할 것으로 사료된다.