반도체 소재의 나노미터 스케일의 변형거동 해석

김동언(Dong-Earn Kim),오수익(Soo-Ik Oh) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

Since all essential property of semiconductor materials are structure-sensitive, the understanding of the deformation mechanism and the deformed structure which can be formed in the nanometer-scale devices is very crucial. To investigate the deformation mechanism and the corresponding structures, nanometer-scale contact loading simulations are carried out using molecular dynamics in silicon and gallium-arsenide.

Depth-controllable ultra shallow Indium Gallium Zinc Oxide/Gallium Arsenide hetero junction diode

Yang, S.U.,Choi, S.H.,Lee, J.,Kim, J.,Jung, W.S.,Yu, H.Y.,Roh, Y.,Park, J.H. Elsevier Sequoia 2013 JOURNAL OF ALLOYS AND COMPOUNDS Vol.561 No.-

One of the challenges for the III-V semiconductor-based nanometer-scale device fabrication is to achieve ultra-shallow junction diode. In this letter, we demonstrate a junction depth-controllable ultra-shallow (15nm) n-IGZO/p-GaAs hetero-junction diode at a low temperature (300<SUP>o</SUP>C). Through TOF-SIMS, J-V measurement, and HSC chemistry simulation, n-IGZO/p-GaAs junctions are carefully investigated. On-current density (0.02A/cm<SUP>2</SUP>) and on/off-current ratio (4x10<SUP>2</SUP>) were obtained in the junction annealed at 300<SUP>o</SUP>C. Additionally, the effect of n-IGZO thickness control on junction current is investigated, comparing 15nm and 30nm thick n-IGZO samples.

Gallium Arsenide (GaAs) Nanofibers by Electrospinning Technique as Future Energy Server Materials

Sheikh, Faheem A.,Barakat, Nasser A.M.,Kanjwal, Muzafar A.,Park, S.J.,Kim, Hern,Kim, Hak-Yong 한국섬유공학회 2010 FIBERS AND POLYMERS Vol.11 No.3

Gallium arsenide (GaAs) does have superior electronic properties compared with silicon. For instant, it has a higher saturated electron velocity and higher electron mobility. Weak mechanical properties and high production cost are the main drawbacks of this interesting semiconductor. In this study, we are introducing production of GaAs nanofibers by electrospinning methodology as a very low cost and yielding distinct product technique. In general, nano-fibrous shape is strongly improving the physical properties due to the high surface area to volume ratio of this nanostructure. The mechanical and environmental properties of the GaAs compound have been modified since GaAs nanofibers have been produced as a core inside a poly(vinyl alcohol) (PVA) shell. GaAs/PVA nanofibers were prepared by electrospinning of gallium nitrate/PVA solution in presence of arsenic vapor. The whole process was carried out in a closed hood equipped with nitrogen environment. FT-IR, XPS, TGA and UV-Vis spectroscopy analyses were utilized to confirm formation of GaAs compound. Transmission electron microscope (TEM) analysis has revealed that the synthesized GaAs compound is crystalline and does have nano-fibrous shape as a core inside PVA nanofibers. To precisely recommend the prepared GaAs nanofiber mats to be utilized in different applications, we have measured the electric conductivity and the band gap energies of the prepared nanofiber mats. Overall, the obtained results affirmed that the proposed strategy successfully remedied the drawbacks of the reported GaAs structures and did not affect the main physical properties of this important semiconductor.

Terahertz emission characteristics of GaMnAs dilute magnetic semiconductor under 650 mT external magnetic field

Alexander De Los Reyes,Elizabeth Ann Prieto,Karim Omambac,Jeremy Porquez,Lorenzo Lopez Jr.,Karl Cedric Gonzales,John Daniel Vasquez,Mae Agatha Tumanguil,Joselito Muldera,Kohji Yamamoto,Masahiko Tani,A 한국물리학회 2017 Current Applied Physics Vol.17 No.4

We investigate the effects of an externally applied magnetic field on the terahertz (THz) emission of Gallium Manganese Arsenide (GaMnAs) films grown via molecular beam epitaxy (MBE). Results show that low Mn-doping in GaMnAs resulted to increased THz emission as compared with a SI-GaAs substrate. Further increase in Mn-doping content resulted to a comparably less THz emission, which is attributed to reduced crystallinity and higher free-carrier absorption. Under an external magnetic field, the contributions of the Bup and Bdown-related THz emission were observed to be asymmetric: possibly due to intrinsic magnetic properties of GaMnAs.

Three-Temperature Modeling of Carrier-Phonon Interactions in Thin GaAs Film Structures Irradiated by Picosecond Pulse Lasers

Seong Hyuk Lee,Junghee Lee,Kwan-Gu Kang,Joon Sik Lee 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.8

This article investigates numerically the carrier-phonon interactions in thin gallium arsenide (GaAs) film structures irradiated by subpicosecond laser pulses to figure out the role of several recombination processes on the energy transport during laser pulses and to examine the effects of laser fluences and pulses on non-equilibrium energy transfer characteristics in thin film structures. The self-consistent hydrodynamic equations derived from the Boltzmann transport equations are established for carriers and two different types of phonons, i.e., acoustic phonons and longitudinal optical (LO) phonons. From the results, it is found that the two-peak structure of carrier temperatures depends mainly on the pulse durations, laser fluences, and nonradiative recombination processes, two different phonons are in nonequilibrium state within such lagging times, and this lagging effect can be neglected for longer pulses. Finally, at the initial stage of laser irradiation, SRH recombination rates increases sufficiently because the abrupt increase in carrier number density no longer permits Auger recombination to be activated. For thin GaAs film structures, it is thus seen that Auger recombination is negligible even at high temperature during laser irradiation.

In Vitro 자계(磁界) 측정에 의한 비소화합물의 폐포 Macrophage 독성 평가

조영채,Cho, Young-Chae 대한예방의학회 1999 Journal of Preventive Medicine and Public Health Vol.32 No.4

Objectives: This study was conducted to evaluate the cytotoxicity of gallium arsenide(GaAs), indium phosphide(InP) and indium arsenide(InAs) all of which are used a$ the semiconductor eletments in semiconductor industry. Methods: Cytotoxicity id the alveolar macrophage was evaluated by the measurement of in vitro magnetometry, LDH release assay and histological examination. Results: The relaxation curves by the in vitro magnetometry showed that GaAs has the cytotoxicity for the alveolar macrophage which is more significant in the higher dosages, while this cytotoxicity is not appeared in the groups added with InP or InAs or PBS. In the decay constant for two minutes after magnetization, GaAs-added groups showed a significant decrease with increasing doses, but both InP- and InAs-added groups did not show any significance. The LDH release assay showed a dose-dependent increasing tendency in the GaAs-, InP- and InAs-added groups. In terms of cellular morphological changes, GaAs-added groups revealed such severe cellular damages as prominent destructions in cell membranes and their morphological changes of nucleus, while InP- and InAs-added groups remained intact in intracellular structures, except for cytoplasmic degenerations. Conclusions: It is suggested that GaAs is more influential to cytotoxicity of alveolar macrophages than InP and InAs. 본 연구는 반도체 산업에서 반도체소자로서 주목받고 있는 GaAs, InP및 InAs의 세포독성을 평가하기 위해 햄스터의 폐포 대식세포를 사용하여 in vitro 자계 측정, LDH 활성치측정 및 세포의 형태학적 관찰 등을 검토하였다. 세포자계측정 결과 GaAs, InP 및 InAs첨가군 모두 대조군(PBS첨가군)에 비해 완화곡선이 유의하게 지연되었으며, 특히 GaAs 첨가군은 농도증가에 따라 용량의존적으로 완화곡선이 지연되는 경향이었다. 자화 후 2분간의 완화계수는 대조군에 비해 GaAs 첨가군은 농도증가에 따라 유의하게 낮아지는 용량의존성이 높은 경향이었으나, InP 및 InAs 첨가군에서는 모두 유의성이 인정되지 않았다. LDH활성치는 GaAs, InP 및 InAs첨가군 모두 용량 의존적으로 점차 높아지는 경향이었다. 세포의 형태학적 관찰소견은 GaAs첨가군에서는 용량의존적으로 세포막의 현저한 파괴, 핵의 형태적 변화 등 심한 세포장해가 유발된 반면, InP첨가군과 InAs첨가군에서는 세포내의 구조는 유지되었으나 세포질의 변성이 관찰되었다. 결과적으로 GaAs는 InP나 InAs보다 폐포 대식세포의 세포독성이 강한 것으로 보인다.

Three-Temperature Modeling of Carrier-Phonon Interactions in Thin GaAs Film Structures Irradiated by Picosecond Pulse Lasers

Lee Seong-Hyuk,Lee Jung-Hee,Kang Kwan-Gu,Lee Joon-Sik The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.8

This article investigates numerically the carrier-phonon interactions in thin gallium arsenide (GaAs) film structures irradiated by subpicosecond laser pulses to figure out the role of several recombination processes on the energy transport during laser pulses and to examine the effects of laser fluences and pulses on non-equilibrium energy transfer characteristics in thin film structures. The self-consistent hydrodynamic equations derived from the Boltzmann transport equations are established for carriers and two different types of phonons, i.e., acoustic phonons and longitudinal optical (LO) phonons. From the results, it is found that the two-peak structure of carrier temperatures depends mainly on the pulse durations, laser fluences, and nonradiative recombination processes, two different phonons are in nonequilibrium state within such lagging times, and this lagging effect can be neglected for longer pulses. Finally, at the initial stage of laser irradiation, SRH recombination rates increases sufficiently because the abrupt increase in carrier number density no longer permits Auger recombination to be activated. For thin GaAs film structures, it is thus seen that Auger recombination is negligible even at high temperature during laser irradiation.

Control of Crack Formation for the Fabrication of Crack-Free and Self-Isolated High-Efficiency Gallium Arsenide Photovoltaic Cells on Silicon Substrate

Oh, Sewoung,Jun, Dong Hwan,Shin, Keun Wook,Choi, InHye,Jung, Sang Hyun,Choi, JeHyuk,Park, Wonkyu,Park, Yongjo,Yoon, Euijoon IEEE 2016 IEEE journal of photovoltaics Vol.6 No.4

<P>We proposed a new scheme, controlling the crack formation by notch patterns, to fabricate self-isolated high-efficiency gallium arsenide (GaAs)-based solar cells on a silicon (Si) substrate. The notch patterns introduced into the Si substrate were found to successfully generate the crack-free areas of 2 mm x 2 mm size separated by the cracks for the 5.8-mu m-thick GaAs layers on it. The individual solar cells on the crack-free areas were confirmed to be electrically isolated from one another by the well-defined crack array. The open-circuit voltage and the efficiency of the crack-free cell were improved to 0.87 V and 18.0%, respectively, from 0.78 V and 14.7% for the cell with 33.2 cm(-1) of linear crack density.</P>

A Study of the Quantitative Relationship of Charge-Density Changes and the Design Area of a Fabricated Solar Cell

In-Sung Kim,Seon-Hun Kim,Hoy-Jin Kim,Sang-Hyun Kim,Kyeong-Nam Jeon 한국전기전자재료학회 2011 Transactions on Electrical and Electronic Material Vol.12 No.5

In this paper, the design area of a fabricated solar cell has been analyzed with respect to its charge density. The mathematical calculation used for charge-density derivation was obtained from the 2001 version of a MATHCAD program. The parameter range for the calculations was ±1 × 10^(17) cm^(-3), which is in the normal parameter range for n-type doping impurities (7.0 × 10^(17) cm^(-3)) and also for p-type impurities (4.0 × 10^(17) cm^(-3)). Therefore, it can be said that the fabricated solar-cell design area has a direct effect on charge-density changes.

The Effect of Interfacial Dipoles on the Metal-Double Interlayers-Semiconductor Structure and Their Application in Contact Resistivity Reduction

Kim, Sun-Woo,Kim, Seung-Hwan,Kim, Gwang-Sik,Choi, Changhwan,Choi, Rino,Yu, Hyun-Yong American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.51

<P>We demonstrate the contact resistance reduction for III-V semiconductor-based electrical and optical devices using the interfacial dipole effect of ultrathin double interlayers in a metal-interlayers-semiconductor (M-I-S) structure. An M-I-S structure blocks metal-induced gap states (MIGS) to a sufficient degree to alleviate Fermi level pinning caused by MIGS, resulting in contact resistance reduction. In addition, the ZnO/TiO2 interlayers of an M-I-S structure induce an interfacial dipole effect that produces Schottky barrier height (Phi(B)) reduction, which reduces the specific contact resistivity (rho(c)) of the metal/n-type III-V semiconductor contact. As a result, the Ti/ZnO(0.5 nm)/TiO2(0.5 nm)/n-GaAs metal-double interlayers-semiconductor (M-DI-S) structure achieved a rho(c) of 2.51 x 10(-5) Omega.cm(2), which exhibited an similar to 42 000x reduction and an similar to 40X reduction compared to the Ti/n-GaAs metal-semiconductor (M-S) contact and the Ti/TiO2(0.5 nm)/n-GaAs M-I-S structure, respectively. The interfacial dipole at the ZnO/TiO2 interface was determined to be approximately -0.104 eV, which induced a decrease in the effective work function of Ti and, therefore, reduced Phi(B). X-ray photoelectron spectroscopy analysis of the M-DI-S structure also confirmed the existence of the interfacial dipole. On the basis of these results, the M-DI-S structure offers a promising nonalloyed Ohmic contact scheme for the development of III-V semiconductor-based applications.</P>