• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.353-358
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• 2008

In order to increase extraction efficiency of AlGaInP-based vertical RED LEDs, chemical wet etching technique was produced by using a roughened surface with triangle-like morphology. A commonly used $H_3PO_4$-based solution was applied for chemical wet etching. The light extraction of AlGaInP LED was related to the n-side roughed surface morphology. The morphology of roughed surface is analyzed by the atomic force microscope (AFM). As a result, the roughed surface AlGaInP LED has a root-mean-square (RMS) roughness of 44 nm. The brightness shows 41% increase after roughening n-side surface, as compared to the ordinary flat surface LED.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.68-72
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• 2004

The integrated voltage-controlled-oscillator(VOC) operating at 1.75 ㎓ is designed using the InGaP/GaAs HBT process. The proposed noise removal circuit and FR-4 substrate structure in this letter show the better characteristic of the phase noise and reduce the size of the VCO. The frequency tuning range of the VCO is about 200 ㎒ and the phase noise at 120 ㎑ offset is -119.3 ㏈c/㎐. The power consumption of the VCO core is 11.2 ㎽ at 2.8 V supply voltage and the output power is -2 ㏈m. The calculated figure of merit(FOM) is 191.7, which shows the best performance compared with the previous FET or HBT VCO.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.414-414
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• 2013

InGaAlAs/InP은 $1.3{\sim}1.55{\mu}m$ 레이저 다이오드 응용을 위한 InGaAsP/InP를 대체하기 위한 물질로 많은 관심을 받아왔다. 디지털 합금 InGaAlAs 다중양자우물(multiple quantum wells: MQWs) 시료는 MBE (molecular beam epitaxy) 장비를 이용하여 n-InP 기판 위에 성장하였다. 양자우물과 장벽은 각각 (InGaAs)0.8(InAlAs)0.2와 (InGaAs)0.4(InAlAs)0.6 SPSs (short-period superlattices)로 $510^{\circ}C$에서 성장하였다. 발광특성을 향상시키기 위하여 질소분위기에서 $700^{\circ}C$ $750^{\circ}C$ 또는 $800^{\circ}C$에서 30초간 열처리(rapid thermal annealing: RTA)하였다. RTA 온도에 따른 디지털 합금 InGaAlAs MQWs의 발광특성을 분석하기 위해 PL (photoluminescence)과 TRPL(time-resolved PL)을 이용하였다. RTA 온도에 따른 InGaAlAs MQWs 시료의 발광 메카니즘 및 운반자 동력학을 연구하기 위하여 발광파장 및 온도에 따른 TRPL을 측정하였다. 저온(10 K)에서 PL 피크는 RTA 온도를 $700^{\circ}C$에서 $750^{\circ}C$로 증가하였을 때 1,242 nm에서 1,245 nm로 장파장 영역으로 이동하였다가 $800^{\circ}C$에서 열처리하였을 때 단파장 영역으로 이동하여 1,239 nm에서 나타났다. 또한 PL 세기는 RTA 온도를 증가함에 따라 증가함을 보이다가 RTA 온도를 $800^{\circ}C$로 증가하였을 때 PL 세기는 감소하였다. 발광소자 개발을 위한 InAlGaAs MQWs 시료의 최적의 열처리 조건을 이러한 PL과 TRPL 결과로부터 결정할 수 있다.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.687-694
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• 1994

Heteroepitaxial InP/GaAs layers were grown using the selective liquid phase epitaxy (SLPE) technique. It was observed that the optimum LPE conditions were $660^{\circ}C$ growth temperature, $5^{\circ}C$ supercooling, and $0.4^{\circ}C$/min cooling rate. Maximum expitaxial layer overgrowth (ELO) of 110-160$\mu \textrm{m}$ was obtained when the seed was aligned along (112) orientation. Initial melt-back of the substrate was observed but limited to the seed region so that flat In-Ga-As-P layers were grpwn throughout the GaAs substrates. The InP/GaAs heteroepitaxial structure could be obtained by growing an additional InP layer on top of the In-Ga-As-P layer.

• 전기의세계
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• v.28 no.4
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• pp.53-63
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• 1979

Interface recombination velocity in $Al_{x}$G $a_{1-x}$ As-GaAs and $Al_{0.85}$, G $a_{0.15}$ As-GaA $s_{1-y}$S $b_{y}$ heterojunction systems is studied as a function of lattice mismatch. The results are applied to the design of highly efficient III-V heterojunction solar cells. A horizontal liquid-phase epitaxial growth system was used to prepare p-p-p and p-p-n $Al_{x}$G $a_{1-x}$ As-GaA $s_{1-y}$S $b_{y}$-A $l_{x}$G $a_{1-x}$ As double heterojunction test samples with specified values of x and y. Samples were grown at each composition, with different GaAs and GaAs Sb layer thicknesses. A method was developed to obtain the lattice mismatch and lattice constants in mixed single crystals grown on (100) and (111)B oriented GaAs substrates. In the AlGaAs system, elastic lattice deformation with effective Poisson ratios .mu.$_{eff}$ (100=0.312 and .mu.$_{eff}$ (111B) =0.190 was observed. The lattice constant $a_{0}$ (A $l_{x}$G $a_{1-x}$ As)=5.6532+0.0084x.angs. was obtained at 300K which is in good Agreement with Vegard's law. In the GaAsSb system, although elastic lattice deformation was observed in (111) B-oriented crystals, misfit dislocations reduced the Poisson ratio to zero in (100)-oriented samples. When $a_{0}$ (GaSb)=6.0959 .angs. was assumed at 300K, both (100) and (111)B oriented GaAsSb layers deviated only slightly from Vegard's law. Both (100) and (111)B zero-mismatch $Al_{0.85}$ G $a_{0.15}$As-GaA $s_{1-y}$S $b_{y}$ layers were grown from melts with a weight ratio of $W_{sb}$ / $W_{Ga}$ =0.13 and a growth temperature of 840 to 820 .deg.C. The corresponding Sb compositions were y=0.015 and 0.024 on (100) and (111)B orientations, respectively. This occurs because of a fortuitous in the Sb distribution coefficient with orientation. Interface recombination velocity was estimated from the dependence of the effective minority carrier lifetime on double-heterojunction spacing, using either optical phase-shift or electroluminescence timedecay techniques. The recombination velocity at a (100) interface was reduced from (2 to 3)*10$^{4}$ for y=0 to (6 to 7)*10$^{3}$ cm/sec for lattice-matched $Al_{0.85}$G $a_{0.15}$As-GaA $s_{0.985}$S $b_{0.015}$ Although this reduction is slightly less than that expected from the exponential relationship between interface recombination velocity and lattice mismatch as found in the AlGaAs-GaAs system, solar cells constructed from such a combination of materials should have an excellent spectral response to photons with energies over the full range from 1.4 to 2.6 eV. Similar measurements on a (111) B oriented lattice-matched heterojunction produced some-what larger interface recombination velocities.ities.ities.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.693-696
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• 2004

For InGaP/GaAs HBT applications, we have developed characterized MIM capacitors with thin $1000{\AA}$ PECVD silicon nitride which were deposited with $SiH_4/NH_3$ gas mixing rate, working pressure, and RF power of PECVD at $300^{\circ}C$ and had the capacitance density of 600 pF/$mm^2$ with the breakdown electric fields of 3073 MV/cm. Three PECVD process parameters were designed to lower the refractive index and then lower the deposition rate of silicon nitride films for the high breakdown electric field. At the PECVD process condition of gas mixing rate (0.92), working pressure (1.3 Torr), RF power (53 W), the AFM Rms value of about $1000{\AA}$ silicon nitride on the bottom metal was the lowest of 0.662 nmand breakdown electric fields were the highest of about 73 MV/cm.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.10-11
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• 2000

광통신을 이용한 근거리 전송과 장거리 전송에서 1.3 및 1.55 $mu extrm{m}$ 파장 영역의 빛이 사용되고 있다. 향후, 각 가정마다 광선로를 연결하는 Fiber-to-the-home (FTTH)의 개념과 광CATV가 발전함에 따라 1.3 및 1.55 $\mu\textrm{m}$ 빛을 검출하는 소자와 송신하는 소자가 필요하게 된다. 본 논문에서는 이러한 다중파장을 검출할 수 있는 집적소자를 제작 및 측정하였다. 본 논문에서 사용된 epitaxial layer의 구조는 N-InP 기판 위에 1 $\mu\textrm{m}$의 n-InP buffer층, 5층의InGaAs/InGaAsP 다중양자우물과 0.2 $\mu\textrm{m}$ InGaAsP separate confinement heterostructure (SCH) 층, 0.5$\mu\textrm{m}$ InP clad층과 0.1 $\mu\textrm{m}$ InGaAs cap 층으로 구성되어있다. 모든 epi 층은 InP 기판에 격자 정합이 되어있다. 다중양자우물구조는 84 $\AA$의 InGaAs 우물층과 100 $\AA$의 InGaAsP 장벽층으로 구성되며, 상온에서 0.787 eV (1.575 $\mu\textrm{m}$)의 bandgap energy를 갖도록 설계하였다. (중략)

• Journal of the Korean Vacuum Society
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• v.11 no.4
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• pp.207-211
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• 2002

Band gap tuning by quantum well disordering in $In_{0.53}Ga_{0.47}As/InGaAsP(Q1.25)$ quantum well structure has been investigated using photoluminescence. The threshold temperature for the blue shift was about $750^{\circ}C$ , and the blue shift became larger as the annealing temperature increased. $SiO_2$ showed saturation as the annealing temperature increased. $SiN_x$caused larger blue shift than $SiO_2$, which is considered to be related to the low growth temperature of $SiN_x$. The diffusion of P and Ga are thought to be responsible for the blue shift of the $SiN_x$ and $SiO_2$capped quantum well disordering , respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.133-133
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• 2010

3-5족 화합물 반도체를 이용한 집광형 삼중 접합 태양전지는 35% 이상의 광변환 효율로 주목을 받고 있다. 일반적으로 삼중 접합 태양전지는 넓은 영역대의 파장을 흡수하기 위해 밴드갭이 다른 InGaP, GaAs, Ge이 사용된다. 그 중 하부셀은 기계적 강도가 높고 장파장을 흡수할 수 있는 Ge이 사용되는데, p-type Ge 기판위에 III-V 결정막 성장 시 5족 원소가 확산되어 pn접합을 형성하게 된다. 이러한 구조를 가진 Ge 하부셀이 효율적으로 홀-전자 쌍을 형성하기 위해서는 두꺼운 베이스와 얇은 에미터 접합이 필요하다. InGaP의 phosphorus는 낮은 확산계수로 인해 GaAs의 arsenic에 비해 얇은 접합이 형성 가능하며, Ge표면 에칭효과가 더 적다는 장점이 있다. 이를 고려해 우리 연구그룹에서는 metalorganic chemical vapor depostion(MOCVD)을 이용하여 Ge기판위에 성장한 InGaP layer의 특성을 관찰해 보았다. <111>로 $6^{\circ}$ 기울어진 p-type Ge(100) 기판위에 MOCVD를 통해 InGaP layer를 형성하였고, 성장된 layer를 atomic force microscope(AFM)와 high-resolution x-ray diffraction(HRXRD)을 이용하여 표면형상, 조성, 응력상태 등을 각각 관찰하였다. 또한 phosphorus 확산에 의해 형성되는 도핑농도는 electrochemical capacitance-voltage(ECV)을 이용하여 관찰하였다. 성장된 Ge기판위의 InGaP layer의 경우 특징적으로 높이 50 nm, 밑변 길이 $1\;{\mu}m$의 경사진 표면을 관찰할 수 있었으며, 이러한 구조는 TMIn과 TMGa의 비율이 증가 할수록 감소하였다. 따라서 이러한 경사진 형태의 구조는 격자 불일치 때문인 것으로 판단된다. 추가적으로 V/III ratio의 최적화를 통해 1.3 nm의 표면 거칠기를 갖는 InGaP layer를 얻을 수 있었다. ECV를 통해 Ge 하부셀의 pn접합 형성을 관찰한 결과 약 160 nm에서 접합이 형성되는 것을 관찰할 수 있었다. 또한, 같은 성장 조건의 샘플을 1000 초 열처리 후에 접합깊이의 변화를 관찰한 결과 180 nm에서 접합이 관찰되었지만, GaAs의 arsenic에 의한 pn접합은 열처리 후에 그 깊이가 170 nm에서 300 nm로 증가 하였다. 따라서 삼중접합 태양전지의 제작 공정을 고려할 경우 phosphorus에 의한 접합 형성이 Ge 하부셀의 동작 특성에 유리할 것으로 판단된다.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1073-1076
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• 2003

This paper shows the performance as a photodetector of InP/InGaAs HPT operated with a base bias and forntside optical injection through the emitter. InP/InGaAs HPT produced the high optical gain of about 16.2 where HPT is biased at Vc=1V, I$_{B}$=20$\mu$A with an input optical power of 2.4$\mu$W. And we examined that the optical gain of HPTs becomes larger when operating in 3-terminal configuration rather than 2-terminal with the floating base. The optical performance of InP/InGaAs HPT is an attractive to the PIN Photodetector for use in long wavelength optical receivers.s.