• ETRI Journal
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• v.11 no.4
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• pp.75-83
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• 1989

The diffusion mechanism of Si in GaAs was investigated using different diffusion sources based on the Si-Ga-As ternary phase equilibria. The Si profiles are measured with secondary ion mass spectrometry and differ significantly for sources taken from the different phase fields in the ternary phase diagram. Neutral As vacancy diffusion is proposed for acceptor Si diffusion anneals using a Ga - Si - GaAs source. Donor Si diffusion using As - rich sources and a Si -GaAs tie line source shows concentration dependent diffusion behavior. Concentration dependent diffusion coefficients of donor Si for As - rich source diffusion were found to be related to net ionized donor concentration and showed three regimes of different behavior: saturation regime, intermediate regime,and intrinsic regime. Ga vacancies are proposed to be responsible for donor Si diffusionin GaAs: $Si_Ga^+V_Ga^-$ (donor Si -acceptor Gavacancy) complex for the extrinsic regime and neutral $V_G$a, for the intrinsic regime.The Si - GaAs tie line source resulted in two branch profiles, intermediate between the As - rich and the Ga - rich source diffusion cases.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.51-59
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• 1995

(001)방향 GaAs 기판과 Si/Co 박막의 계면반응 및 상평형에 관한 연구를 300-$700^{\circ}C$ 열처리 구간에서 행하였다. 반응에 의한 상전이 과정은 glancing angle X-ray diffraction(GXRD), Auger electron spectroscopy(AES) 및 cross-sectional transmission electron microscopy(GXRD), Auger electron spectroscopy(AES) 및 corss-sectional transmission electron microscopy(XTEM)을 이용하여 분석하였다. Si/Co/GaAs계의 계면반응에서 Co는 $380^{\circ}C$에서 GaAs 기판 및 Si와 반응하여 Co2GaAs과 Co2Si상을 형성하였다. $420^{\circ}C$에서 열처리 후, Co층은 모두 소모되었으며 단면구조는 Si/CoSi/CoGa(CoAs)/Co2GaAs/GaAs으로 전이되었다. $460^{\circ}C$까지 온도를 올려 계속적인 반응을 일으키면 CoGa와 CoAs이 분해되면서 CoSi가 성장하였고, $600^{\circ}C$에서는 Co2GaAs마저 분해되고 CoSi상이 성장하여 GaAs와 계면을 형성하였다. CoSi와 GaAs사이의 계면은 $700^{\circ}C$의 고온까지 안정하였으며 이러한 계면반응 결과는 계산에 의하여 구한 Si-Co-Ga-As 4원계 상태도로부터 이해될 수 있었다.

• Solar Energy
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• v.18 no.3
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• pp.137-146
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• 1998

In this paper, the current status of manufacturing technologies for GaAs/Si solar cell were revived and provied new MOCVD. In the manufacturing process of GaAs/Si solar cells and an experiment to get the high efficiency GaAs solar cells, we must investigate the optimum growth conditions to get high quality GaAs films on Si substrates by MOCVD. The GaAs on Si substrates has been recognized as a lightweight alternative to pure substrate for space applicaton. Because its density is less the half of GaAs or Ge.So GaAs/Si has twofold weight advantage to GaAs monolithic cell. The theoretical conversion efficiecy limit of tandem GaAs/Si solar cell is 32% under AM 0 and $25^{\circ}C$ condition. It was concluded that the development of cost effective MOCVD technologies shoud be ahead GaAs solar cells for achived move high efficiency III-V solar cells involving tandem structure.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.5
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• pp.380-386
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• 1991

Hydrogen plasma-assisted epitaxial(PAE) growth of GaAs/Si and GaAs/Ge/Si with Ge buffer layer has been investigated. By means of photoluminescence, Nomarski microscopu, and $\alpha$-step, it could be known that GaAs on Si with Ge buffer layer has better crystalline quality than GaAs on Si without Ge buffer layer. The stoichiometry of GaAs layer on Si was confirmed by the depth profile of Auger electron spectroscope (AES). Also the native oxide(SiO$_2$) layer on Si substrate was plama-etched and the removal of the oxide layer was confirmed by AES. Photoluminescence peak wavelength of GaAs/Ge/Si with Ge buffer of 1\ulcorner thickness and GaAs growth rate of 160$\AA$/min was 8700$\AA$and FWHM was 12$\AA$.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.79-82
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• 1989

We studied the epitaxial growth of GaAs/GaAs and GaAs/Si by Laser CVD with 193nm ArF pulsed excimer laser. The source gases of TMGa and AsC13 or TMGa-TMAs adducts are mixed with H2, and photolyzed above the substrate which is heated up to around 300$^{\circ}C$. Then the photolyzed atoms are deposited on the silicon or GaAs substrate. The deposited films are analyzed with ESKA depth profiling and X-ray differaction method, which shows that the films on Si and GaAs are stoichiometric and crystalized at such a low temperature. We show a clear evidence for the epitaxial growth of GaAs on Si or GaAs on GaAs at low temperature by excimer laser CVD.

• Journal of Surface Science and Engineering
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• v.43 no.4
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• pp.170-175
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• 2010

The GaAs epitaxial layers were grown on Si(100) substrates by molecular beam epitaxy(MBE) using the two-step method. The Si(100) substrates were cleaned with different surface cleaning method of vacuum heating, As-beam, and Ga-beam at the substrate temperature of $800^{\circ}C$. Growth temperature and thickness of the GaAs epitaxial layer were $800^{\circ}C$ and 1 ${\mu}m$, respectively. The surface structure and epitaxial growth were observed by reflection high-energy electron diffraction(RHEED) and scanning electron microscope(SEM). Just surface structure of the Si(100) substrate cleaned by Ga-beam at $800^{\circ}C$ shows double domain ($2{\times}1$). RHEED patterns of the GaAs epitaxial layers grown on Si(100) substrates with cleaning method of vacuum heating, As-beam, and Ga-beam show spot-like, ($2{\times}4$) with spot, and clear ($2{\times}4$). From SEM, it is found that the GaAs epitaxial layers grown on Si(100) substrates with Ga-beam cleaning has a high quality.

• Journal of the Korean Vacuum Society
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• v.19 no.5
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• pp.371-376
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• 2010

The GaAs epitaxial layers were grown on Si(100) substrates by molecular beam epitaxy (MBE) using the two-step method. The Si(100) substrates were cleaned with three different surface cleaning methods of vacuum heating, As-beam exposure, and Ga-beam deposition at the substrate temperature of $800^{\circ}C$ in the MBE growth chamber. Growth temperature and thickness of the GaAs epitaxial layer were $800^{\circ}C$ and $1{\mu}m$, respectively. The surface structure and properties were investigated by reflection high-energy electron diffraction (RHEED), AFM (Atomic force microscope), DXRD (Double crystal x-ray diffraction), PL (Photoluminescence), and PR (Photoreflectance). From RHEED, the surface structure of GaAs epitaxial layer grown on Si(100) substrate with Ga-beam deposition is ($2{\times}4$). The GaAs epitaxial layer grown on Si(100) substrate with Ga-beam deposition has a high quality.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.150-154
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• 2000

We investigated the quantum well intermixing (QWI) of a compressively strained InGaAs/InGaAsP multiple quantum well (MQW) by using impurity free vacancy diffusion technique. The samples with InGaAs/$SiO_2$ capping layer showed a higher degree of intermixing compared to that of InP/$SiO_2$ capping layer after rapid thermal annealing (RTA). Band-gap shift difference as large as 123 meV (195 nm) was observed between samples capped with InGaAs/$SiO_2$ and with InP/$SiO_2$ layer at RTA temperature of $700^{\circ}C$. Using the InGaAs/$SiO_2$ cap layer, the band-gap wavelength of MQW was changed by the intermixing from 1.55 $\mu\textrm{m}$ band to 1.3 $\mu\textrm{m}$ band with a wavelength shift of a 237 nm. The transform from MQW structure to homogenous alloy was observed above the RTA temperature of $700^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1672-1678
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• 1989

Major problems preventing the device-quality GaAs/Si heterostructure are the lattice mismatch of about 4% and difference in thermal expansion coefficient by a factor of 2.64 between Si and GaAs. Ge is a good candidate for the buffer layer because its lattice parameter and thermal expansion coefficient are almost the same as those of GaAs. As a first step toward developing heterostructure such as GaAs/Ge/Si entirely by a home-built PAE (plasma-assisted epitaxy), Ge films have been deposited on p-type Si (100)substrate by the plasma assisted evaporation of solid Ge source. The characteristics of these Ge/Si heterostructure were determined by X-ray diffraction, SEM and Auge electron spectroscope. PAE system has been successfully applied to quality-good Ge layer on Si substrate at relatively low temperature. Furthermore, this system can remove the native oxide(SiO2) on Si substrate with in-situ cleaning procedure. Ge layer grown on Si substrate by PAE at substrate temperature of 450\ulcorner in hydrogen partial pressure of 10mTorr was expected with a good buffer layer for GaAs/Ge/Si heterostructure.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.218-227
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• 2003

Pd/Si/Ti/Pt and Pd/Si/Pd/Ti/Au ohmic contacts to n-type InCaAs were investigated for applications to AlGaAs/GaAs HBT emitter ohmic contacts. In the Pd/Si/Ti/Pt ohmic contact, as-deposited contact showed non-ohmic behavior, and high specific contact resistivity of $5\times10^{-3}\Omega\textrm{cm}^2$ was achieved by rapid thermal annealing at $375^{\circ}C$/10 sec. However, the specific contact resistivity decreased remarkably to $2\times10^{-6}\Omega\textrm{cm}^2$ by annealing at $425^{\circ}C$/10sec. In the Pd/Si/Pd/Ti/Au ohmic contact, minimum specific contact resistivity of $3.9\times10^{-7}\Omega\textrm{cm}^2$ was achieved by annealing at $400^{\circ}C$/20sec. In both ohmic contacts, low contact resistivity and non-spiking planar interface between ohmic materials and InGaAs were maintained. Therefore, these thermally stable ohmic contact systems are promising candidates for compound semiconductor devices. RF performance of the AlGaAs/GaAs HBT was also examined by employing the Pd/Si/Ti/Pt and Pd/Si/Pd/Ti/Au systems as emitter ohmic contacts. Cutoff frequencies were 63.9 ㎓ and 74.4 ㎓, respectively, and maximum oscillation frequencies were 50.1 ㎓ and 52.5 ㎓, respectively. It shows very successful high frequency operations.