• 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.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.698-702
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• 2000

The characteristics of optical absorption in $Al_{0.24}Ga_{0.76}As/GaAs$ multi-quantum wells(MQWs) structure were investigated by using the surface photovoltage(SPV). The Spy features near 1.42 eV showed two overlapping signals. By chemical etching, we found associated with the GaAs substrate and the GaAs cap layer. The Al composition(x=24 %) was determined by Kuech's composition formula. In order to identify the transition energies. the experimentally observed energies were compared with results of the envelope function approximation for a rectangular quantum wells An amplitude variation of the relative Spy intensity from the GaAs substrate, llH, and llL was observed at different light intensities. A variation in the SPY line shape of the transition energies were observed with decreasing tempera­t ture.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.352-357
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• 2009

The InAs multi-quantum dots (MQDs) solar cell and InGaAs multi-quantum wells (MQWs) solar cell to cover 1.1 eV and 1.3 eV were designed by 1D poisson, respectively. The MQDs and MQWs of 5, 10, 15 layers were grown by molecular beam epitaxy. The photo luminescence results showed that the 5 period stacked MQDs have the highest intensity at around 1.1 eV with 57.6 meV full width at half maximum (FWHM). Also we can observe 10 period stacked MQWs peak position which has highest intensity at 1.31 eV with 12.37 meV FWHM. The density and size of QDs were observed by reflection high energy electron diffraction pattern and atomic force microscope. Futhermore, AlGaAs/GaAs sandwiched tunnel junctions were modified according to the width of GaAs layer on p-type GaAs substrates. The structures with GaAs width of 30 nm and 50 nm have backward diode characteristics. In contrast, tunnel diode characteristics were observed in the 20 nm of that of sample.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.1
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• pp.21-27
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• 2000

We used the surface photovoltage spectroscopy(SPVS) for characterization of GaAs/Al\ulcornerGa\ulcornerAs multi-quantum well(MQW) structures grown by molecular beam epitaxy(MBE) method. Energy gap related transitions in GaAs and AlGaAs were observed. The Al composition(x=0.3) was determined by Sek's composition formula. Transition energies in MQW were determined using the differential surface photo-volatage spectroscopy)DSPVS) of the measured resonanced. In order to indentify the transitions, the experimentally observed energies were compared with results of the envelope function approximation for a rectangular quantum well. We have observed and interesting behavior of the temperature dependence(80K~300K) of the 11Hand 11L transition for sample.

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.200-201
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• 1998

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.9
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• pp.23-30
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• 2000

The performance of two types of surface reflecting all-optical switches with InGaAs/InAlAs multiple quantum wells are investigated. The absorption spectra and the refractive index changes of the quantum well are calculated for various pump and probe beam intensities and device conditions. From theses results, on ON/OFF ratio and switching speed of the two switches are compared. It is shown that the switch using DBR has higher ON/OFF ratio and higher switching speed than the switch without DBR.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.440-444
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• 1996

In this paper, we report an InGaAs/InAlAs multi-quantum well (MQW) avalanche photodiode (APD) showing a performance suitable for 10 Gbps lightwave communications. In designing the device, emphasis is given on the effect of indiffusion of Be dopant from the highly doped field layer into the MQW multiplication region. It is found that a small amount of diffusion can alter the dark current and gain characteristics of the device significantly. A spacer used to restrain such indiffusion is shown effective in reducing dark current (500 nA at a gain of 10) while maintaining a high bandwidth (10 GHz at a gain of 10) devices grown by molecular beam epitaxy.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.02a
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• pp.184-184
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 2005.08a
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• pp.99-99
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• 2005

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.328-333
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• 1998

Lattice-matched InAIAs epilayers were grown on (001) InP substrate by low pressure metalorganic chemical vapor deposition. The effects of growth conditions on the properties of InAIAs were analyzed, and InGaAs/InAIAs single and multiple quantum wells were successfully grown. It was observed that the optical property of InAIAs epilayers was improved in the temperature range of 620~$700^{\circ}C$ as the growth temperature increased due to the reduction of oxygen incorporation, however, the crystallinity decreased at temperatures higher than $750^{\circ}C$ due to the degraded crystallinity of the bufter layers. The enhanced incorporation of AI into epilayer was observed at high $AsH_3$flow rates and it was explained in terms of the differences in bond strengths of AI-As and In-As. The measured photoluminescence peak energies from InGaAs/InAIAs single quantum wells were consistent with the calculated ones based on transfer matrix method. High-order satellite peaks and fine thickness fringes were observed by high-resolution x-ray diffraction, implying that the high-quality multiple quantum wells with abrupt heterointerfaces were grown.