• 전자공학회논문지A
• /
• 제31A권10호
• /
• pp.71-78
• /
• 1994

We have developed GaAs power metal semiconductor field effect transistors (MESFETs) for 4.7V operation under 900 MHz using a low-high deped structures grown by molecular beam epitaxy (MBE). The fabricted MESFETs with a gate widty of 7.5 mm and a gate length of 1.0.mu.m show a saturated drain current (Idss) of 1.7A and an uniform transconductance (Gm) of around 600mS, for gate bias ranged from -2.4 V to 0.5 V. The gate-drain breakdown voltage is measured to be higher than 25 V. The measured rf characteristics of the MESFETs at a frequency of 900 MHz are the output power of 31.4 dBm and the power added efficiency of 63% at a drain bias of 4.7 V.

• 한국전기전자재료학회논문지
• /
• 제23권4호
• /
• pp.343-346
• /
• 2010

We have investigated growth of CdTe thin films by using (As, GaAs) buffer layers for application of large scale IR focal plane arrays(IFPAs). Buffer layers were grown by molecular beam epitaxy(MBE), which reduced the lattice mismatch of CdTe/Si and prevented native oxide on Si substrates. CdTe thin films were grown by metal organic chemical deposition system(MOCVD). As a result, polycrystalline CdTe films were grown on Si(100) and arsenic coated-Si(100) substrate. In other case, single crystalline CdTe(400) thin film was grown on GaAs coated-Si(100) substrate. Moreover, we observed hillock structure and mirror like surface on the (400) orientated epitaxial CdTe thin film.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
• /
• pp.205-208
• /
• 2001

Schottky barrier diodes are fabricated on a intrinsic GaN(4${\mu}{\textrm}{m}$) epitaxial structure grown by rf plasma molecular beam epitaxy (MBE) on sapphire substrates. First, We make Ohmic electrodes (Ti/Al/Ti/Au) by evaporator. Next, we contact RuO$_2$ by dipping in the solution (RuCl$_3$.HClO$_4$), and then we deposit Ni/Au on the surface of RuO$_2$ by evaporator. We study the electrical characteristics of GaN Schottky barrier diodes made by these methods. Measurements are C-V, I-V, SEM, EDX, and XRD for the characteristics of devices. Thickness of RuO$_2$ layer depends on supplied voltage and dipping time. Device of thinner RuO$_2$ layer have a good Schottky characteristics compare with device of thicker RuO$_2$ layer

• 전자공학회논문지A
• /
• 제31A권9호
• /
• pp.114-120
• /
• 1994

We have been successfully fabricated the low nois HEMT device with AlGaAs and GaAs structure. The epitazial layer with n-type AlgaAs and undoped GaAs was grown by molecular beam epitaxy(MBE) system. Ohmic resistivity of the ource and drain contact is below 5${\times}10^{6}{\Omega}{\cdot}cm^{2}$ by the rapid thermal annealing (RTA) process. The ideality factor of the Schottky gate is below 1.6 and the gate material was Ti/Pt/Au. The HEMTs with 0.25$\mu$m-long and 200$\mu$m-wide gates have exhibited a noise figure of 0.65dB with associated gain of 9dB at 12GHz, and a transconductance of 208mS/mm.

• 한국전기전자재료학회논문지
• /
• 제13권1호
• /
• pp.21-27
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.78-79
• /
• 2005

We report on optically excited terahertz (THz) omission from low-temperature (LT) grown GaAs. We have used 70 fs titanium-sapphire laser pulses with wavelengths at 800 nm to generate THz radiation pulses. The LT-GaAs layers are grown on semi-insulating GaAs substrates with GaAs buffer layer by molecular beam epitaxy (MBE). The THz emission from the LT-GaAs surface is strong and does not show any significant variation in the strength of the THz emission over several different angles between the polarization of the excitation laser pulse and the crystallographic orientation of the LT-GaAs.

• Transactions on Electrical and Electronic Materials
• /
• 제2권2호
• /
• pp.16-20
• /
• 2001

Optoelectronic characteristics of the superlattice diode as a function of deposition temperature and annealing conditions have been studied. The multilayer nanocrystalline silicon/adsorbed oxygen (nc/Si/O) superlattice formed by molecular beam epitaxy (MBE) system. Experimental results showed that deposition temperature of 550$^{\circ}C$, followed by hydrogen annealing leads to best results, in terms of optical photoluminescence (PL) and electrical current-voltage (I-V) characteristics. Consequently, the experimental results of multilayer Si/O superlattic device showed the stable photoluminescence and good insulating behavior with high breakdown voltage. This is very useful promise for Si-based optoelectronic devices, and can be readily integrated with conventional silicon ULSI processing.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.459-459
• /
• 2013

Si (111) 기판 위에 plasma assisted molecular beam epitaxy 법으로 Si과 Mg doping된 GaN 나노막대를 각 각 성장하고 나노막대의 모양과 광학적 특성을 조사하였다. Si이 doping된 GaN 나노막대는 biaxial m-plane 방향의 변화로 별 모양을 갖는 것을 관찰하였고 Mg doping된 GaN 나노막대의 지름은 줄어드는 것을 scanning electron microscopy로 확인하였다. 본 연구에서는 이러한 변화의 원인을 stress 때문으로 보고 x-ray diffraction과 raman scattering 측정을 통하여 구조적 변화를 조사하였다. 또한, stress에 의한 GaN 나노막대의광학적 특성 변화를 photoluminescence을 통하여 조사하였다. Doping한 GaN 나노막대의 특성조사를 통해 GaN 나노막대 성장 시 발생되는 stress의 영향을 이해하는데 중요한 정보를 제공할 것이다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.485-485
• /
• 2013

Plasma-assisted molecular beam epitaxy법으로 자가 형성되는 InN 박막을 활용하여 GaN 박막의 결함밀도를 감소시키는 성장 구조 조건에 대하여 연구하였다. Sapphire 기판 위에 저온에서 GaN 핵층을 3 nm 두께로 성장하고, 그 위에 InN 박막을 성장 한 후, 고온에서 GaN을 성장하였다. InN박막의 성장 온도는 $450^{\circ}C$이고, 성장 시간을 30초에서 1분 30초까지 각각 달리 하였다. 실험결과 InN 층이 삽입된 GaN 박막이 상대적으로 고른 표면이 형성되는 과정을 reflection high energy electron diffraction로 관측하였고, atomic force microscope를 측정하여 표면 거칠기의 개선을 확인하였다. InN 성장시간 변화에 따른 결정학적, 광학적 특성 변화를 x-ray diffraction, photoluminescence 이용하여 조사하였고, 본 연구를 통해 InN박막을 활용한 양질의 GaN 박막 성장 가능성을 확인하였다.

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
• /
• pp.3-7
• /
• 1998

The rare-earth ions (R3+, R=Nd, Er) doped CaF2 layers have been grown on CaF2(111) substrate by molecular beam epitaxy. The epitaxial relationship and the crystallinity of CaF2:R3+ layers depending on the concentration of R3+ were studied by reflection high-energy electron diffraction (RHEED). In aspect of application as buffer layer in semiconductor-related hybrid structure, the lattice displacement between CaF2:R3+ layers and CaF2(111) substrate was investigated by X-ray rocking curve analysis.