• Title/Summary/Keyword: Optoelectronic properties

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Exciton dissociation yields of semiconducting polymer thin film devices doped by various phosphorescent emitters

  • An, J.D.;Chang, J.Y.;Han, J.W.;Im, C.;Chin, B.D.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1010-1013
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    • 2006
  • To understand the exact charge carrier photogeneration properties of photoactive thin films consisting of a ${\pi}-conjugated$ polymer matrix and a triplet dopant, we prepared two types of polymer, poly(9-vinylcarbazole) (PVK) and poly[9,9-bis(2- ethylhexyl)fluorene-2,7-diyl] (PF2/6) doped with triplet emitters for organic light-emitting diodes (OLED), either iridium(III)fac-tris(2-phenylpyridine) $(Ir(ppy)_3)$ or iridium(III)bis[(4,6-fluorophenyl)- $pyridinato-N,C^2'$]picolinate (FIrpic), as thin film devices by using the conventional method. Those doped film devices, as well as pristine film devices, on ITO substrates were characterized by means of steady state photocurrent measurement for a wide spectral range.

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Optoelectronic Properties of Semiconductor-Atomic Superlattice Diode for SOI Applications (SOI 응용을 위한 반도체-원자 초격자 다이오드의 광전자 특성)

  • 서용진
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.3
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    • pp.83-88
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    • 2003
  • The optoelectronic characteristics of semiconducto-atomic superlattice as a function of deposition temperature and annealing conditions have been studied. The nanocrystalline silicon/adsorbed oxygen superlattice formed by molecular beam epitaxy(MBE) system. As an experimental result, the superlattice with multilayer Si-O structure showed a stable photoluminescence(PL) and good insulating behavior with high breakdown voltage. This is very useful promise for Si-based optoelectronics and quantum devices as well as for the replacement of silicon-on-insulator (SOI) in ultra-high speed and lower power CMOS devices in the future, and it can be directly integrated with silicon ULSI processing.

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PL spectra of disorderd InGaAs/InGaAsP quantum wells (원자섞임처리한 InGaAs/InGaAsP 양자우물의 PL 스펙트럼 특성)

  • Lee, Jong-Chang;Choi, Won-Jun;Lee, Seok;Woo, Duk-Ha;Kim, Sun-Ho;Choi, Sang-Sam
    • Proceedings of the Optical Society of Korea Conference
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    • 2000.02a
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    • pp.258-259
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    • 2000
  • Quantum Well Disordering (QWD) has drawn a considerable attention in recent years$^{(1-3)}$ due to its wide applicability to optoelectronic devices. QWD allows modification of the shape of QW in selected regions, hence it modifies the subband energies in conduction and valance bands$^{(4)}$ . This leads to changes in optical properties such as band gap, absorption coefficient and refractive index. Thus such disordering in selected areas enables monolithic integration of various optoelectronic devices such as lasers, EA/EO modulators, waveguides and optical amplifiers. In this paper, we investigate the quantum well disordering effects on photoluminescence spectra by using experimental measurements and theoretical analysis$^{(5)}$ . (omitted)

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A Review of Electronic Devices Based on Halide Perovskite Materials (할라이드 페로브스카이트 소재를 이용한 전자 소자에 관한 리뷰)

  • Hyeong Gi Park;Jungyup Yang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.5
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    • pp.519-526
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    • 2024
  • This review examines the use of halide perovskite materials in electronic devices, highlighting their exceptional optoelectronic properties and the challenges associated with them. Despite their potential for high-performance devices, practical applications are limited by sensitivity to environmental factors such as moisture and oxygen, etc. We discuss advances in enhancing stability and operational reliability, featuring innovative synthesis methods and device engineering strategies that help mitigate degradation. Furthermore, we explore the integration of perovskites in applications such as field-effect transistors and LEDs, emphasizing their transformative potential. This review also outlines future research directions, stressing the need for ongoing improvements in material stability and device integration to fully realize the commercial potential of perovskites.

Fabrication of Patchable Organic Lasing Sheets via Soft Lithography

  • Kim, Ju-Hyung
    • Clean Technology
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    • v.22 no.3
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    • pp.203-207
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    • 2016
  • Here, we report a novel fabrication technique for patchable organic lasing sheet based on non-volatile liquid organic semiconductors and freestanding polymeric film with high flexibility and patchability. For this work, we have fabricated the second-order DFB grating structure, which leads to surface emission, embedded in the freestanding polymeric film. Using an ultra-violet (UV) curable polyurethaneacrylate (PUA) mixture, the periodic DFB grating structure can be easily prepared on the freestanding polymeric film via a simple UV curing process. Due to unsaturated acrylate remained in the PUA mixture after UV curing, the freestanding PUA film provides adhesive properties, which enable mounting of the patchable organic lasing sheet onto non-flat surfaces with conformal contact. To achieve laser actions in the freestanding resonator structure, a composite material of liquid 9-(2-ethylhexyl)carbazole (EHCz) and organic laser dyes was used as the laser medium. Since the degraded active materials can be easily refreshed by a simple injection of the liquid composite, such a non-volatile liquid organic semiconducting medium has degradation-free and recyclable characteristics in addition to other strong advantages including tunable optoelectronic responses, solvent-free processing, and ultimate mechanical flexibility and uniformity. Lasing properties of the patchable organic lasing sheet were also investigated after mounting onto non-flat surfaces, showing a mechanical tunability of laser emission under variable surface curvature. It is anticipated that these results will be applied to the development of various patchable optoelectronic applications for light-emitting displays, sensors and data communications.

Recent Progress of Nonpolar and Semipolar GaN on Sapphire Substrates for the Next Generation High Power Light Emitting Diodes

  • Lee, Seong-Nam
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.05a
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    • pp.20.2-20.2
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    • 2011
  • III-nitrides have attracted much attention for optoelectronic device applications whose emission wavelengths ranging from green to ultraviolet due to their wide band gap. However, due to the strong polarization properties of conventional c-plane III-nitrides, the built-in polarization-induced electric field limits the performance of optical devices. Therefore, there has been a renewed interest in the growth of nonpolar III-nitride semiconductors for polarization free heterostructure optoelectronic and electronic devices. However, the crystal and the optical quality of nonpolar/semipolar GaN have been poorer than those of conventional c-plane GaN, resulting in the relative poor optical and electrical properties of light emitting diodes (LEDs). In this presentation, I will discuss the growth and characterization of high quality nonpolar a-plane and semipolar (11-22) GaN and InGaN multiple quantum wells (MQWs) grown on r- and m-plane sapphire substrates, respectively, by using metalorganic chemical vapor deposition (MOCVD) without a low temperature GaN buffer layer. Especially, the epitaxial lateral overgrowth (ELO) technique will be also discussed to reduce the dislocation density and enhance the performance of nonpolar and semipolar GaN-based LEDs.

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Detection of Volatile Organic Compounds (VOCs) using Organic-Inorganic Hybrid Perovskite Nanoparticles (유무기 페로브스카이트 나노입자의 휘발성 유기화합물 감응특성)

  • Choi, Hansol;Choi, Jihoon
    • Korean Journal of Materials Research
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    • v.30 no.10
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    • pp.515-521
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    • 2020
  • Organic-inorganic hybrid perovskite nanocrystals have attracted a lot of attention owing to their excellent optical properties such as high absorption coefficient, high diffusion length, and photoluminescence quantum yield in optoelectronic applications. Despite the many advantages of optoelectronic materials, understanding on how these materials interact with their environments is still lacking. In this study, the fluorescence properties of methylammonium lead bromide (CH3NH3PbBr3, MAPbBr3) nanoparticles are investigated for the detection of volatile organic compounds (VOCs) and aliphatic amines (monoethylamine, diethylamine, and trimethylamine). In particular, colloidal MAPbBr3 nanoparticles demonstrate a high selectivity in response to diethylamine, in which a significant photoluminescence (PL) quenching (~ 100 %) is observed at a concentration of 100 ppm. This selectivity to the aliphatic amines may originate from the relative size of the amine molecules that must be accommodated in the perovskite crystals structure with a narrow range of tolerance factor. Sensitive PL response of MAPbBr3 nanocrystals suggests a simple and effective strategy for colorimetric and fluorescence sensing of aliphatic amines in organic solution phase.

Optical Characteristics of Oxygen-doped ZnTe Thin Films Deposited by Magnetron Sputtering Method

  • Kim, Seon-Pil;Pak, Sang-Woo;Kim, Eun-Kyu
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.253-253
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    • 2011
  • ZnTe semiconductor is very attractive a material for optoelectronic devices in the visible green spectral region because of it has direct bandgap of 2.26 eV. The prototypes of ZnTe light emitting diodes (LEDs) have been reported [1], showing that their green emission peak closely matches the most sensitive region of the human eye. The optoelectronic properties of ZnTe:O film allow to expect a large optical gain in the intermediate emission band, which emission band lies about 0.4-0.6 eV below the conduction band of ZnTe [2]. So, the ZnTe system is useful for the production of high-efficiency multi-junction solar cells [2,3]. In this work, the ZnTe:O thin films were deposited on Al2O3 substrates by using the radio frequency magnetron sputtering system. Three sets of samples were prepared using argon and oxygen as the sputtering gas. The deposition chamber was pre-pumped down to a base pressure of 10-7 Torr before introducing gas. The deposition pressure was fixed at 10-3 Torr throughout this work. During the ZnTe deposition, the substrate temperature was 300 oC. The optical properties were also investigated by using the ultraviolte-visible (UV-Vis) spectrophotometer.

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A Class of Check Matrices Constructed from Euclidean Geometry and Their Application to Quantum LDPC Codes

  • Dong, Cao;Yaoliang, Song
    • Journal of Communications and Networks
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    • v.15 no.1
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    • pp.71-76
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    • 2013
  • A new class of quantum low-density parity-check (LDPC) codes whose parity-check matrices are dual-containing matrices constructed based on lines of Euclidean geometries (EGs) is presented. The parity-check matrices of our quantum codes contain one and only one 4-cycle in every two rows and have better distance properties. However, the classical parity-check matrix constructed from EGs does not satisfy the condition of dual-containing. In some parameter conditions, parts of the rows in the matrix maybe have not any nonzero element in common. Notably, we propose four families of fascinating structure according to changes in all the parameters, and the parity-check matrices are adopted to satisfy the requirement of dual-containing. Series of matrix properties are proved. Construction methods of the parity-check matrices with dual-containing property are given. The simulation results show that the quantum LDPC codes constructed by this method perform very well over the depolarizing channel when decoded with iterative decoding based on the sum-product algorithm. Also, the quantum codes constructed in this paper outperform other quantum codes based on EGs.

Effects of Lattice Mismatch on Photoluminescence Efficiency of InGaAsP/InP Heterostructures (InGaAsP/InP이종접합구조의 격자부정합이 Photoluinescence효율에 미치는 영향)

  • Lee, Jong-Won
    • Korean Journal of Materials Research
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    • v.4 no.5
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    • pp.516-523
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    • 1994
  • The interfacial coherency of metal organic chemical vapor deposition grown InGaAsP/InP heterostructure wafers was examined and their influences on the optoelectronic properties were investigated in this study. (400) symmetric and (511) asymmetric reflections were employed to measure the lattice coherency. Existence of misfit dislocations was examined by x-ray topography and reverified by photoluminescence (PL) imaging. PI, measurements were performed, and higher PL intensity was obtained for elastically strained samples and lower intensity for plastically deformed samples. The highest PL intensity was obtained for the sample lattice matched at the growth temperature. PL full-width at half maximum (FWHM) was found to depend on the degree of lattice mismatch. A correlatior between x-ray FWHM and PL intensity was empirically established. The results presented demonstrate that the interfacial coherency is of primary significance in affecting the optoelectronic properties through elastic strain and plastic deformation.

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