RF 마그네트론 코스퍼터링을 이용한 Si₃N₄ 매트릭스 내부의 실리콘 양자점 제조연구

하린,김신호,이현주,박영빈,이정철,배종성,김양도,Ha, Rin,Kim, Shin-Ho,Lee, Hyun-Ju,Park, Young-Bin,Lee, Jung-Chul,Bae, Jong-Seong,Kim, Yang-Do 한국재료학회 2010 한국재료학회지 Vol.20 No.11

Films consisting of a silicon quantum dot superlattice were fabricated by alternating deposition of silicon rich silicon nitride and $Si_3N_4$ layers using an rf magnetron co-sputtering system. In order to use the silicon quantum dot super lattice structure for third generation multi junction solar cell applications, it is important to control the dot size. Moreover, silicon quantum dots have to be in a regularly spaced array in the dielectric matrix material for in order to allow for effective carrier transport. In this study, therefore, we fabricated silicon quantum dot superlattice films under various conditions and investigated crystallization behavior of the silicon quantum dot super lattice structure. Fourier transform infrared spectroscopy (FTIR) spectra showed an increased intensity of the $840\;cm^{-1}$ peak with increasing annealing temperature due to the increase in the number of Si-N bonds. A more conspicuous characteristic of this process is the increased intensity of the $1100\;cm^{-1}$ peak. This peak was attributed to annealing induced reordering in the films that led to increased Si-$N_4$ bonding. X-ray photoelectron spectroscopy (XPS) analysis showed that peak position was shifted to higher bonding energy as silicon 2p bonding energy changed. This transition is related to the formation of silicon quantum dots. Transmission electron microscopy (TEM) and electron spin resonance (ESR) analysis also confirmed the formation of silicon quantum dots. This study revealed that post annealing at $1100^{\circ}C$ for at least one hour is necessary to precipitate the silicon quantum dots in the $SiN_x$ matrix.

Observation of Single Electron Transport via Multiple Quantum States of a Silicon Quantum Dot at Room Temperature

Lee, Sejoon,Lee, Youngmin,Song, Emil B.,Hiramoto, Toshiro American Chemical Society 2014 NANO LETTERS Vol.14 No.1

<P>Single electron transport through multiple quantum levels is realized in a Si quantum-dot device at room-temperature conditions. The energy spacing of more than triple the omnipresent thermal energy is obtained from an extremely small ellipsoidal Si quantum dot, and high charge stability is attained through a construction of the gate-all-around structure. These properties may move us a step closer to practical applications of quantum devices at elevated temperatures. An in-depth analysis on the transport behavior and quantum structure is presented.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-1/nl403204k/production/images/medium/nl-2013-03204k_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl403204k'>ACS Electronic Supporting Info</A></P>

Newly Synthesized Silicon Quantum Dot–Polystyrene Nanocomposite Having Thermally Robust Positive Charge Trapping

Dung, Mai Xuan,Choi, Jin-Kyu,Jeong, Hyun-Dam American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.7

<P>Striving to replace the well known silicon nanocrystals embedded in oxides with solution-processable charge-trapping materials has been debated because of large scale and cost effective demands. Herein, a silicon quantum dot–polystyrene (SiQD–PS) nanocomposite (NC) was synthesized by post-functionalization of hydrogen-terminated silicon quantum dots (H-SiQDs) with styrene using a thermally induced surface-initiated polymerization approach. The NC contains two miscible components: PS and SiQD@PS which, respectively, are polystyrene and polystyrene chains-capped SiQDs. Spin-coated films of the nanocomposite on various substrate were thermally annealed at different temperatures and subsequently used to construct metal-insulator-semiconductor (MIS) devices and thin film field-effect transistors (TFTs) having a structure of p-Si<SUP>++</SUP>/SiO<SUB>2</SUB>/NC/pentacene/Au source-drain. Capacitance–voltage (<I>C</I>–<I>V</I>) curves obtained from the MIS devices exhibit a well-defined counterclockwise hysteresis with negative fat band shifts, which was stable over a wide range of curing temperatures (50–250 °C). The positive charge trapping capability of the NC originates from the spherical potential well structure of the SiQD@PS component while the strong chemical bonding between SiQDs and polystyrene chains accounts for the thermal stability of the charge trapping property. The transfer curve of the transistor was controllably shifted to the negative direction by varying applied gate voltage. Thereby, this newly synthesized and solution processable SiQD–PS nanocomposite is applicable as charge trapping materials for TFT based memory devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-7/am400356r/production/images/medium/am-2013-00356r_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am400356r'>ACS Electronic Supporting Info</A></P>

Preparation of Water-soluble Silicon quantum dots through microwave reactor from monosaccharides

조성호,인인식,최유진,채아리,권빈희,정우준,박종엽,주단비,( Nur`aeni ) 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Recently, plenty intense research interests have been focused on the development of water-soluble fluorescence quantum dots. Many researches have reported that highly fluorescent and water-dispersible SiQDs using silicon source and organic capping agent. This silicon-based SiQDs are many applications including photo-catalysis, light-emitting displays, and even bio-imaging. Herein, we reported simply synthetic method via microwave reactor using monosaccharides and silicon resources in non-harsh condition. The resulting SiQDs show high luminescence and good-solubility in aqueous media together with extremely low cytotoxicity with extremely low cytotoxicity and environmental friendly. Further detailed characterization of monosaccharidebased SiQDs will be discussed in detail. ^**2016년 한국교통대학교 지원을 받아 수행하였음.

Effect of Auger recombination induced by donor and acceptor states on luminescence properties of silicon quantum Dots/SiO₂ multilayers

Joo, Beom Soo,Jang, Seunghun,Gu, Minseon,Jung, Namsik,Han, Moonsup ELSEVIER SCIENCE 2019 Journal of Alloys and Compounds Vol.801 No.-

<P><B>Abstract</B></P> <P>Impurity doping is a key factor that needs to be addressed to control the optical properties of silicon quantum dots (Si QDs) for their applications in optoelectronic devices. Although there have been several studies to understand the effect on n-type and p-type dopant on the luminescence properties of Si QDs, the exact influence of the dopant impurities on the optical properties and the underlying mechanism are yet to be understood. For this purpose, we investigate the luminescence properties of Si QDs/SiO<SUB>2</SUB> multilayer structure doped with B and P. Using rf-magnetron sputtering and ion implantation techniques, we prepared three kinds of samples: undoped, B-doped and <I>P</I>-doped. Results from photoluminescence measurements indicate that the significant luminescence suppression in the doped samples can be mainly attributed to the Auger non-radiative process occurring between photoexcited excitons and free carriers. Our interpretation should serve to resolve the controversy around the effect of impurity doping on the luminescence properties of Si QDs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fabricating the silicon quantum dots embedded in SiO<SUB>2</SUB> by rf-magnetron sputtering. </LI> <LI> Boron and phosphorus doping to the silicon quantum dot by ion implantation methods. </LI> <LI> Observing the significant luminescence suppression in doped silicon quantum dots. </LI> <LI> The luminescence quenching in doped Si QDs is attributed to the non-radiative Auger process of excess free carriers. </LI> </UL> </P>

Thermal Curing Property of Silicone Encapsulant Containing Quantum Dot Surrounded by Various Types of Ligands

Lee, Chae Sung,Kim, BeomJong,Jeon, Seongun,Han, Cheul Jong,Hong, Sung-Kyu Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.12

In this study, the silicone thermal curing degree of the silicone-encapsulated quantum dot light emission diode was measured using the various types of chemical ligands around quantum dot. It was confirmed that the trioctyl phosphin oxide (TOPO) ligand around the quantum dot was responsible for dispersion of the quantum dot in silicone encapsulant and decline of the thermal curing degree of the silicone encapsulant. Also, it was confirmed that the thermal curing degree of silicone encapsulants containing the steric acid (SA) and the dodecanoic acid (DA) ligands were higher than the one of TOPO ligand.

Thermal Curing Property of Silicone Encapsulant Containing Quantum Dot Surrounded by Various Types of Ligands

Chae Sung Lee,BeomJong Kim,Seongun Jeon,한철종,홍성규 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.12

In this study, the silicone thermal curing degree of the silicone-encapsulated quantum dot light emission diode was measured using the various types of chemical ligands around quantum dot. It was confirmed that the trioctyl phosphin oxide (TOPO) ligand around the quantum dot was responsible for dispersion of the quantum dot in silicone encapsulant and decline of the thermal curing degree of the silicone encapsulant. Also, it was confirmed that the thermal curing degree of silicone encapsulants containing the steric acid (SA) and the dodecanoic acid (DA) ligands were higher than the one of TOPO ligand.

Study on the Fabrication of Silicon Nanoparticles in an Amorphous Silicon Light Absorbing Layer for Solar Cell Applications

박주형,송진수,Jae Hee Lee,이정철 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.12

Hydrogenated amorphous-silicon (a-Si:H) thin-film solar cells have advantages of relatively simple technology, less material consumption, higher absorption ratio compared to crystalline silicon, and low cost due to the use of cheaper substrates rather than silicon wafers. However, together with those advantages, amorphous-silicon thin-film solar cells face several issues such as a relatively lower efficiency, a relatively wider bandgap, and the Staebler-Wronski effect (SWE) compared to other competing materials (<i>i.e.</i>, crystalline silicon, CdTe, Cu(In_xGa_(1−x))Se₂ (CIGS), <i>etc.</i>). As a remedy for those drawbacks and a way to enhance the cell conversion efficiency at the same time, the employment of crystalline silicon nanoparticles (Si-NPs) in the a-Si matrix is proposed to organize the quantum-dot (QD) structure as the light-absorbing layer. This structure of the light absorbing layer consists of single-crystal Si-NPs in an a-Si:H thin-film matrix. The single-crystal Si-NPs are synthesized by using SiH4 gas decomposition with CO₂ laser pyrolysis, and the sizes of Si-NPs are calibrated to control their bandgaps. The synthesized size-controlled Si-NPs are directly transferred to another chamber to form a QD structure by using co-deposition of the Si-NPs and the a-Si:H matrix. Transmission electron microscopy (TEM) analyses are employed to verify the sizes and the crystalline properties of the Si-NPs alone and of the Si-NPs in the a-Si:H matrix. The TEM results show successful co-deposition of size-controlled Si-NPs in the a-Si:H matrix, which is meaningful because it suggests the possibility of further enhancement of the a-Si:H solar-cell structure and of tandem structure applications by using a single element.

Manufacture and Characterization on Three-Dimensional Random Resonators of Porous Silicon/TiO2 Nanowires for Continuous Light Pumping Lasing of Perovskite Quantum Dots

Yining Mu,Tuo Zhang,Tianqi Chen,Fanqi Tang,Jikai Yang,Chunyang Liu,Zhangxiaoxiong Chen,Yiming Zhao,Peng Du,Haibo Fan,Yan Zhu,Guozhen Liu,Ping Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.03

In recent years, all inorganic bismuth lead-halide perovskite nanocrystals [CsPbX3 (X=Cl, Br, I)] have received extensive attention due to their high performance in fluorescence quantum yield, narrow emission spectrum, and adjustable emission range. However, the disadvantages of high cost and poor stability have greatly limited the development prospects of the material. Here, in order to develop a perovskite quantum dot lasing cavity with high chemical stability, high quality factor and low fabrication cost, we have successfully fabricated a 3D random cavity device based on porous silicon/TiO2 nanowires. A TiO2 nanowire is grown on the porous silicon to form a 3D resonant cavity, and a perovskite quantum dot is spin-coated on the surface of the 3D resonant cavity to form a novel 3D complex film. The novel structure enhances the chemical stability and lasing quality factor of the resonant cavity while the fluorescence generated by the large quantum dots in the spatial interference structure constitutes the feedback loop, which will provide favorable support for the development of information optics.

Synthesis of Styryl-Terminated Silicon Quantum Dots: Reconsidering the Use of Methanol

Mai Xuan Dung,Hyun-Dam Jeong 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.12