http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
조일욱,류미이,송진동 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.8
The optical properties of InP/InGaP quantum structures (QSs) grown by using a migrationenhanced molecular beam epitaxy method have been investigated using temperature (T)-dependent photoluminescence (PL) and time-resolved PL. InP QSs were grown by varying the growth temperature from 440 C to 520 C. InP/InGaP QS samples grown at temperatures of 440 C - 480 C show typical characteristics of a QS, such as rapid bandgap shrinkage at high T and enhanced PL lifetime at low T while the sample grown at 520 C exhibits the properties of bulk InP. The growth temperature is found to determine the formation of the InP/InGaP QSs; thus, it significantly affects the structural and the optical properties of the InP/InGaP QSs. The best luminescence properties are demonstrated by the sample grown at 460 C, indicating an optimum growth temperature of 460 C.
디지털 합금 InGaAlAs 다중 양자 우물의 열처리 온도에 따른 발광 특성
조일욱,변혜령,류미이,송진동,Cho, Il Wook,Byun, Hye Ryoung,Ryu, Mee-Yi,Song, Jin Dong 한국진공학회 2013 Applied Science and Convergence Technology Vol.22 No.6
디지털 합금(digital alloy) InGaAlAs 다중 양자 우물(multiple quantum wells: MQWs) 구조의 열처리(rapid thermal annealing: RTA) 온도에 따른 발광 특성을 PL (photoluminescence)와 TRPL (time-resolved PL)를 이용하여 분석하였다. $700^{\circ}C$에서 $850^{\circ}C$까지 온도를 변화시켜 RTA한 디지털 합금 MQWs의 PL 결과는 $750^{\circ}C$에서 RTA한 시료가 가장 강한 PL 세기와 가장 좁은 반치폭을 나타내었다. 이것은 $750^{\circ}C$에서 30초 동안 RTA하였을 때 비발광 재결합 센터가 감소하고 가장 매끄러운 경계면이 형성되는 것을 나타낸다. RTA 온도를 $800^{\circ}C$와 $850^{\circ}C$로 증가하였을 때 PL 피크는 청색편이 하였으며 PL 세기는 감소하였다. PL 피크의 청색편이는 RTA 온도가 증가함에 따라 InGaAs/InAlAs SPS (short-period superlattice)의 경계면에서의 Ga과 Al의 혼합(intermixing)으로 Al 함량이 증가한 것으로 설명되며, PL 세기의 감소는 경계면의 거칠기의 증가와 인듐의 상분리(phase separation)로 인한 비균일 조성(compositional fluctuation)으로 설명된다. RTA 온도를 증가하였을 때 PL 소멸시간은 증가하였으며, 이것은 비발광 재결합 센터(결정 결함)가 감소한 것을 나타낸다. 디지털 합금 InGaAlAs MQWs 시료의 PL 특성은 적절한 RTA 조건에서 현저히 향상되는 것을 확인하였다. The effect of rapid thermal annealing (RTA) on the optical properties of digital-alloy InGaAlAs multiple quantum well (MQW) structures have been investigated by using photoluminescence (PL) and time-resolved PL measurements as a function of RTA temperature. The MQW samples were annealed from $700^{\circ}C$ to $850^{\circ}C$ for 30 s in a nitrogen atmosphere. The MQW sample annealed at $750^{\circ}C$ exhibited the strongest PL intensity and the narrowest FWHM (Full width at half maximum), indicating the reduced nonradiative recombination centers and the improved interfaces between the wells and barriers. The MQW samples annealed at $800^{\circ}C$ and $850^{\circ}C$ showed the decreased PL intensities and blueshifted PL peaks compared to $750^{\circ}C$-annealed sample. The blueshift of PL peak with increasing RTA temperatures are ascribed to the increase of aluminum due to intermixing of gallium (Ga) and aluminum (Al) in the interfaces of InGaAs/InAlAs short-period superlattices. The decrease of PL intensity after annealing at $800^{\circ}C$ and $850^{\circ}C$ are attributed to the interface roughening and lateral composition modulation caused by the interdiffusion of Ga and Al and indium segregation, respectively. With increasing RTA temperature the PL decay becomes slower, indicating the decrease of nonradiative defect centers. The optical properties of digital-alloy InGaAlAs MQW structures can be improved significantly with optimum RTA conditions.
조일욱,류미이,송진동 한국진공학회 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 ℃.
조일욱,류미이,송진동 한국진공학회 2016 Applied Science and Convergence Technology Vol.25 No.4
InP/InGaP quantum structures (QSs) grown on GaAs substrates by a migration-enhanced molecular beam epitaxy method were studied as a function of growth temperature (T) using photoluminescence (PL) and emissionwavelength- dependent time-resolved PL (TRPL). The growth T were varied from 440℃ to 520℃ for the formation of InP/InGaP QSs. As growth T increases from 440℃ to 520℃, the PL peak position is blue-shifted, the PL intensity increases except for the sample grown at 520℃, and the PL decay becomes fast at 10 K. Emission-wavelengthdependent TRPL results of all QS samples show that the decay times at 10 K are slightly changed, exhibiting the longest time around at the PL peak, while at high T, the decay times increase rapidly with increasing wavelength, indicating carrier relaxation from smaller QSs to larger QSs via wetting layer/barrier. InP/InGaP QS sample grown at 460℃ shows the strongest PL intensity at 300 K and the longest decay time at 10 K, signifying the optimum growth T of 460℃.
Temperature-dependent luminescence properties of digital-alloy In(Ga1-zAlz)As
류미이,조일욱,송진동 한국진공학회 2018 Applied Science and Convergence Technology Vol.27 No.3
The optical properties of the digital-alloy (In0.53Ga0.47As)1-z/(In0.52Al0.48As)z grown by molecular beam epitaxy as a function of composition z (z = 0.4, 0.6, and 0.8) have been studied using temperature-dependent photoluminescence (PL) and time-resolved PL (TRPL) spectroscopy. As the composition z increases from 0.4 to 0.8, the PL peak energy of the digital-alloy In(Ga1-zAlz)As is blueshifted, which is explained by the enhanced quantization energy due to the reduced well width. The decrease in the PL intensity and the broaden FWHM with increasing z are interpreted as being due to the increased Al contents in the digital-alloy In(Ga1-zAlz)As because of the intermixing of Ga and Al in interface of InGaAs well and InAlAs barrier. The PL decay time at 10 K decreases with increasing z, which can be explained by the easier carrier escape from InGaAs wells due to the enhanced quantized energies because of the decreased InGaAs well width as z increases. The emission energy and luminescence properties of the digital-alloy (InGaAs)1-z/(InAlAs)z can be controlled by adjusting composition z.
Structural and Optical Properties of GaN Nanowires Formed on Si(111)
한상문,최일규,이철로,조일욱,류미이,김진수 한국진공학회 2018 Applied Science and Convergence Technology Vol.27 No.5
We discuss the structural and optical characteristics of GaN nanowires (NWs) grown on Si(111) substrates by a plasmaassisted molecular-beam epitaxy. The GaN NWs with high crystal quality were formed by adopting a new growth approach, so called Ga pre-deposition (GaPD) method. In the GaPD, only Ga was supplied without nitrogen flux on a SiN/Si surface, resulting in the formation of Ga droplets. The Ga droplets were used as initial nucleation sites for the growth of GaN NWs. The GaN NWs with the average heights of 60.10 to 214.62 nm obtained by increasing growth time. The hexagonal-shaped top surfaces and facets were observed from the field-emission electron microscope images of GaN NWs, indicating that the NWs have the wurtzite (WZ) crystal structure. Strong peaks of GaN (0002) corresponding to WZ structures were also observed from double crystal x-ray diffraction rocking curves of the NW samples. At room temperature, free-exciton emissions were observed from GaN NWs with narrow linewidth broadenings, indicating to the formation of high-quality NWs.