• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.282-288
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• 2017

In this paper, GaAs/AlGaAs multi-layer structure was grown by liquid phase epitaxy with graphite sliding boat, which can be used as a device structure of a photocathode image sensor. The multi-layer structure was grown on an n-type GaAs substrate in the sequence as follows: GaAs buffer layer, Zn-doped p-type AlGaAs layer as etching stop layer, Zn-doped p-type GaAs layer, and Zn-doped p-type AlGaAs layer. The Characteristics of GaAs/AlGaAs structures were analyzed by using scanning electron microscope (SEM), secondary ion mass spectrometer (SIMS) and hall measurement. The SEM images shows that the p-AlGaAs/p-GaAs/p-AlGaAs multi-layer structure was grown with a mirror-like surface on a whole ($1.25mm{\times}25mm$) substrate. The Al composition in the AlGaAs layer was approximately 80 %. Also, it was confirmed that the free carrier concentration in the p-GaAs layer can be adjusted to the range of $8{\times}10^{18}/cm^2$ by hall measurement. In the result, it is expected that the p-AlGaAs/p-GaAs/p-AlGaAs multi-layer structure grown by the LPE can be used as a device structure of a photoelectric cathode image sensor.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.401-404
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• 1998

Recently, InGaP/GaAs HBTs have been much interested as a potential replacement for AlGaAs/GaAs HBTs because of their superior device and material properties. In this paper, DC characteristics of InGaP/GaAs HBTs and the temperature dependance as well as the reliability were investigated comparing with AlGaAs/GaAs HBTs. As a results InGaP/GaAs HBTs produced the superior performance to AlGaAs/GaAs HBTs.

• Journal of the Korean Vacuum Society
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• v.15 no.3
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• pp.280-286
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• 2006

A distributed Bragg reflector (DBR) for the application of $1.3{\mu}m$ vertical cavity surface emitting laser (VCSEL) has grown by digital-alloy AlGaAs layer using the molecular beam epitaxy (MBE) method. The measured reflection spectra of the digital-alloy AlGaAs/GaAs DBR have uniformity in 0.35% over the 1/4 of 3-inch wafer. Furthermore, the TEM image showed that the composition and the thickness of the digital-alloy AlGaAs layer in AlGaAs/GaAs DBR was not affected by the temperature distribution over the wafer whole surface. Therefore, the digital-alloy AlGaAs/GaAs DBR can be used to get higher yield of VCSEL with the active medium of InAs quantum dots whose gain is inhomogeneously broadened.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.421-426
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• 1999

In this paper, we present p-channel GaAs MOSFET having $Al_2O_3$ as gate insulator fabricated on a semi-insulating GaAs substrate, which can be operated in the depletion mode. $1\;{\mu}m$ thick undoped GaAs buffer layer, $4000\;{\AA}$ thick p-type GaAs epi-layer, undoped $500{\AA}$ thick AlAs layer, and $50\;{\AA}$ thick GaAs cap layer were subsequently grown by molecular beam epitaxy(MBE) on (100) oriented semi-insulating GaAs substrate and this wafer was oxidized. AlAs layer was fully oxidized as a $Al_2O_3$ thin film. The I-V, $g_m$, breakdown charateristics of the fabricated GaAs MOSFET showed that wet thermal oxidation of AlAs/GaAs epilayer/S I GaAs was successful in realizing depletion mode p-channel GaAs MOSFET.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.1
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• pp.1-7
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• 2000

In this paper, we present n-channel GaAs MOSFET having $Al_2O_3$ as gate in insulator fabricated on a semi-insulating GaAs substrate. 1 ${\mu}$m thick undoped GaAs buffer layer, 1500 ${\AA}$ thick n-type GaAs, undoped 500 ${\AA}$ thick AlAs layer, and 50 ${\AA}$ GaAs caplayer were subsequently grown by molecular beam epitaxy(MBE) on (100) oriented semi-insulating GaAs substrate oxidized. When it was wet oxidized, AlAs layer was fully converted $Al_2O_3$. The I-V, $g_m$, breakdown charateristics of the fabricated GaAs MOSFET showed that wet thermal oxidation of AlAs/GaAs epilayer/S${\cdot}$I GaAs was suitable in realizing depletion mode GaAs MOSFET.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.116-121
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• 2000

We measured surface photovoltage (SPV) of $Al_{0.24}Ga_{0.76}As/GaAs$ epilayer grown by molecular beam epitixy (MBE). The band gap energies of $Al_{0.24}Ga_{0.76}As/GaAs$ epilayer, GaAs substrate and buffer layer obtained from SPV signals are 1.70, 1.40 and 1.42 eV, respectively. There results are in good agreements with photoreflectance (PR) measurement. The measured SPV intensity of GaAs substrate is three times larger than $Al_{0.24}Ga_{0.76}$Asepilayer by carrier mobility difference. The parameters of Varshni equation were determined from the SPV spectra as a function of temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.289-289
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• 2012

Molecular beam epitaxy 방법으로 성장시킨 AlGaAs/GaAs 다중 양자 우물 구조에 대한 라만 산란 연구를 보고한다. InAs 양자점이 성장된 Si 기판 위에 각기 다른 온도에서 두께 약 1 ${\mu}m$의 GaAs 층을 두 단계로 성장시킨 후 그 위에 AlGaAs/GaAs 다중 양자 우물 구조를 성장시켰다. AlGaAs/GaAs 다중 양자 우물 구조의 광학적 특성에 영향을 주는 GaAs 층의 변형력(stress)의 변화를 알기 위해서 시료의 측면으로부터 공간 분해된 라만 산란 실험을 수행하였다. 라만 산란 실험으로부터 AlGaAs/GaAs 다중 양자 우물 구조가 지니는 모든 종류의 광학 포논을 관측하였으며, 두 단계로 성장시킨 GaAs 층에서의 변형력이 Si 기판으로부터 멀어질수록 성장조건의 변화에 따라서 다르게 전개된다는 것을 파악하였다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.88-93
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• 1998

For the self-aligned AlGaAs/GaAs HBTs, the surface states at the interface between the extrinsic base surface and the passivation nitride is a major cause of degradation of dc characteristics. In this paper the degradation mechanisms of self-aligned AlGaAs/GaAs HBT were analyzed, and GaAs HBTs, which employed an InGaP ledge emitter structure formed by the nonself-aligned process to cover the surface of the extrinsic base and reduce the surface states, produced high reliability. Accoridng to the acceleration lifetime test, the nonself-aligned InGaP/GaAs HBTs produced very reliable dc characteristics comparing with the self-aligned AlGaAs/GaAs HBTs. The activation energy was 1.97eV and MTTF $4.8{\times}10^{8}$ hrs at $140^{\circ}C$ which satisfied the MIL standard.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.424-432
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• 1993

AlGaAs/InGaAs/GaAs pseudomorphic structures have been grown by atmosheric pressure-MOCVD . The Al incorporation efficiency is constant but slightly exceeds the Ga incorporation during the growth of AlGaAs layers at $650^{\circ}C$ . Meanwhile , the In incorporation efficiency is constant but slightly less than the Ga incorporation in InGAAs layers. InGaAs/GaAs QWs were grown and their optical properties were characterized . $\delta$-doped Al0.24Ga0.76As/In0.16 Ga0.84As p-HEMT structures were successfully grown by MOCVD and their transport properties were characterized by Hall effect and SdH measurements. SdH Measurements at 3.7K show clear magnetoresistance oscillations and plateaus in the quantum Hall effect confirming the existence of a two-dimensional electron gas(2DEG) and a parallel conduction through the GaAs buffer layer. The fabricated $1.5\mu\textrm{m}$gatelength p-HEMTs having p-type GaAs in the buffer layer show a high transconductance of 200 mS/mm and a good pinch-off characteristics.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.655-660
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• 2001

Surface photovoltage spectroscopy was used to study $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P/GaAs$ grown by metalorganic chemical vapor deposition(MOCVD). Energy gap related transition in GaAs and $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P$ were observed. By measuring the frequency dependence of $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P/GaAs$, we observed that SPV line shape does not chance, whereas the amplitude change. This results is due to the difference in the lifetimes of the photocarriers in GaAs and in $In_{0.5}(Ga_{1-x}Al_x)_{0.5}P$. We also have evaluated the parameters that describe the temperature dependences of the band gap.