• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.13-16
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• 2000

A quantum-wire field effect transistor(QW-FET) using asymmetric double InGaAs channel and Si-delta doped barrier has been fabricated. It exhibited good modulation and saturation characteristic in the range of ${\mu}\textrm{A}$ current level. For estimated channel width of 150nm QW-FET, maximum transconductance was about 400 mS/mm which is higher than a conventional heterostructure FET(HFET) with the same epi-structure.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.60-73
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• 1997

By introducing a compressive-strained quanternary InGaAsP quantum-wells instead of a conventional ternary InGaAs quantum-wells in 1.55.mu.m DFB-LD, the lasing performances canb e improved and the problems caused by the thickness non-uniformity and the compositional abruptness among the hetero-interpaces canb e relaxed. In this paper, we investigated an iptimum InGaAsP/InGaAsP multiple-quantum-well(MQW) structure as an active layer in a direct-modulated 1.55.mu. DFB-LD from the view point of threshold current, chirping charcteristics, and resonance frequency. The optimum compressive-strained MQW structure was revealed as InGaAsP/InGaAsP structure with strain amount of about 1.2%, number of wells $N_{w}$ of 7, well width $L_{w}$ of 58.agns.. The threshold current density J of 500A/c $m^{2}$, the linewidth enhancement factor a of 1.8, and differential resonance frequency of d $f_{r}$/d(I-I)$^{1}$2/=2GHz/(mA)$^{1}$2/(atI=2 $I_{th}$) were expected in 1.55.mu.m .gamma./4-shifted DFB-LD with the cavity length of 400.mu.m long and kL value of 1.25. These values are considerably improved ones compared to those of 1.55um DFB-LD with InGaAs/InGaAsP MQW which have enhancement factor and the resonance frequence frequency by the detuning of lasing wavelength and gain-peak wavelength. It was found that the linewidth enhancement factor of 20% and differential resonance frequency of 35% without the degradation of the threshold current density could be enhanced in the range of -15nm~-20nm detuning which can be realized by controlling the thickness and Incomposition of InGaAsP well. well.and Incomposition of InGaAsP well. well.

• Korean Journal of Materials Research
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• v.12 no.4
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• pp.296-303
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• 2002

For potential application to quantum mechanical devices, nano-composite thin films, consisting of GaAs quantum dots dispersed in SiO$_2$ glass matrix, were fabricated and studied in terms of structural, chemical, and optical properties. In order to form crystalline GaAs quantum dots at room temperature, uniformly dispersed in $SiO_2$matrix, the composite films were made to consist of alternating layers of GaAs and $SiO_2$in the manner of a superlattice using RF magnetron sputter deposition. Among different film samples, nominal thickness of an individual GaAs layer was varied with a total GaAs volume fraction fixed. From images of High Resolution Transmission Electron Microscopy (HRTEM), the formation of GaAs quantum dots on SiO$_2$was shown to depend on GaAs nominal thickness. GaAs deposits were crystalline and GaAs compound-like chemically according to HRTEM and XPS analysis, respectively. From measurement of optical absorbance using a spectrophotometer, absorption edges were determined and compared among composite films of varying GaAs nominal thicknesses. A progressively larger shift of absorption edge was noticed toward a blue wavelength with decreasing GaAs nominal thickness, i.e. quantum dots size. Band gaps of the composite films were also determined from Tauc plots as well as from PL measurements, displaying a linear decrease with increasing GaAs nominal thickness.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.460-466
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• 1999

The deep level electron traps in AP-MOCVD GaAs/undoped Al\ulcornerGa\ulcornerAs/n-type GaAs heterostructures have been investigated by means of Deep Level Transient Spectroscopy DLTS). In terms of the experimental procedure, GaAs/undoped Al\ulcornerGa\ulcornerAs/n-type GaAs heterostructures were deposited on 2" undoped semi-insulating GaAs wafers by the AP-MOCVD method at $650^{\circ}C$ with TMGa, AsH3, TMAl, and SiH4 gases. The n-type GaAs conduction layers were doped with Si to the target concentration of about 2$\times$10\ulcornercm\ulcorner. The Al content was targeted to x=0.5 and the thicknesses of Al\ulcornerGa\ulcornerAs layers were targeted from 0 to 40 nm. In order to investigate the electrical characteristics, an array of Schottky diodes was built on the heterostructures by the lift-off process and Al thermal evaporation. Among the key results of this experiment, the deep level electron traps at 0.742~0.777 eV and 0.359~0.680 eV were observed in the heterostructures; however, only a 0.787 eV level was detected in n-type GaAs samples without the Al\ulcornerGa\ulcornerAs overlayer. It may be concluded that the 0.787 eV level is an EL2 level and that the 0.742~0.777 eV levels are related to EL2 and residual oxygen impurities which are usually found in MOCVD GaAs and Al\ulcornerGa\ulcornerAs materials grown at $630~660^{\circ}C$. The 0.359~0.680 eV levels may be due to the defects related with the al-O complex and residual Si impurities which are also usually known to exist in the MOCVD materials. Particularly, as the Si doping concentration in the n-type GaAs layer increased, the electron trap concentrations in the heterostructure materials and the magnitude of the C-V hysteresis in the Schottky diodes also increased, indicating that all are intimately related.ated.

• 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 surface engineering
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• v.36 no.4
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• pp.334-338
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• 2003

$BCl_3$고밀도 평판형 유도결합 플라즈마(High Density Planar Inductively Coupled Plasma)를 이용하여 AlGaAs와 InGaP의 건식식각에 대하여 연구하였다. 본 실험에서는 ICP 소스파워(0∼500 W), RIE 척 파워(0-150 W), 공정압력(5∼15 mTorr)의 변화에 따른 AlGaAs와 InGaP의 식각률, 식각단면 그리고 표면 거칠기 등을 분석 하였다. 또, 공정 중 OES(Optical Emission Spectroscopy)를 이용하여 in-situ로 플라즈마를 관찰하였다. $BCl_3$ 유도결합 플라즈마를 이용한 AlGaAs의 식각결과는 우수한 수직측벽도와(>87$^{\circ}$) 깨끗하고 평탄한 표면(RMS roughness = 0.57 nm)을 얻을 수 있었다. 반면, InGaP의 경우에는 식각 후 표면이 다소 거칠어진 것을 확인할 수 있었다. 모든 공정조건에서 AlGaAs의 식각률이 InGaP보다 더 높았다. 이는 $BCl_3$ 유도결합 플라즈마를 이용하여 InGaP을 식각하는 동안 $InCl_{x}$ 라는 휘발성이 낮은 식각부산물이 형성되어 나타난 결과이다. ICP 소스파워와 RIE 척파워가 증가하면 AlGaAs와 InGaP모두 식각률이 증가하였지만, 공정압력의 증가는 식각률의 감소를 가져왔다. 그리고 OES peak세기는 공정압력과 ICP 소스파워의 변화에 따라서는 크게 변화하였지만 RIE 척파워에 따라서는 거의 영향을 받지 않았다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.3
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• pp.141-145
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• 2018

Ni-InGaAs shows promise as a self-aligned S/D (source/drain) alloy for n-InGaAs MOSFETs (metal-oxide-semiconductor field-effect transistors). However, limited thermal stability and instability of the microstructural morphology of Ni-InGaAs could limit the device performance. The in situ deposition of a Pd interlayer beneath the Ni layer was proposed as a strategy to improve the thermal stability of Ni-InGaAs. The Ni-InGaAs alloy layer prepared with the Pd interlayer showed better surface roughness and thermal stability after furnace annealing at $570^{\circ}C$ for 30 min, while the Ni-InGaAs without the Pd interlayer showed degradation above $500^{\circ}C$. The Pd/Ni/TiN structure offers a promising route to thermally immune Ni-InGaAs with applications in future n-InGaAs MOSFET technologies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.221-225
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• 1994

We described the impact ionization rates of electron in GaAs/AlGaAs MQH(multi- quantum well) using EMC(ensenble Monte Carlo) simulation. Hot electron energy of injected into quantum well is increasing nearly liearly due to the applied electric field to the barrier of MQM inspite of various Al mole fraction in AlGaAs or barrier width. Impact ionization rates are decreasing exponentially by increasing Al mole fraction, and they have peak vague due to the barrier width.

• Journal of the Korean Vacuum Society
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• v.20 no.1
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• pp.35-41
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• 2011

In this study, the interface soaking effect in InAs/GaAs strained-layer superlattice (SLS) on crystalline phase modulation has been analyzed by the x-ray diffraction (XRD) curve. The strain variation induced by As and/or Sb soaking was determined by the separation angle between the substrate peak and the 0th-order superlattice satellite peak in the XRD spectra. Contrated that the As/InAs soaking arises minor GaAs-like interfacial layer, the Sb/GaSb soaking induces InSb-like one. The Fourier-transformed curves of the Pendellosung interference oscillation shows that the optimum soaking times of As/InAs and Sb/GaSb are 2 sec and 12 sec, at which the highest crystallineity has, respectively. An anomalous twin-peak phenomenon that a satellite peak splits into two peaks was observed in the SLS structure co-soaked by As and Sb at InAs${\rightarrow}$GaSb interfaces. We suggest that it may be resulted from coexistence of two kinds crystalline phases of InAsSb and GaAsSb due to intermixing of In${\leftrightarrow}$Ga and Sb${\leftrightarrow}$As.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.5
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• pp.230-234
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• 2003

CuPt-type ordering has been observed in Zn-rich $Cd_xZn_{1-x}$Te epilayers grown on (001)GaAs and ZnTe/GaAs(001) substrates. X-ray diffraction, electron beam diffraction, high-resolution transmission electron microscopy and low-temperature photoluminescence have been used to characterize the CuPt-type ordering in Zn-rich $Cd_xZn_{1-x}$Te epilayers.