• 제목/요약/키워드: Multilayer Reflector

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Distributed Bragg Reflector, Microcavity 구조를 갖는 다공질규소의 반사율 스펙트럼 (Reflectance spectrum properties of DBR and microcavity porous silicon)

  • 김영유;김한중
    • 한국결정성장학회지
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    • 제19권6호
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    • pp.293-297
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    • 2009
  • 본 연구에서는 p형 단결정 규소 기판을 에칭시켜 다층구조를 갖는 DBR 및 Microcavity 다공질규소를 제작하고, 그 반사율 스펙트럼을 조사하였다. 그 결과 다층구조를 갖는 다공질규소의 반사율 스펙트럼에서 프린지 패턴의 수는 단일층 다공질규소의 경우보다 상대적으로 많았으며, 특정 파장에서 반사율은 90 % 이상으로 나타났다. 그리고 DBR 다공질규소에서 최대 반사율 봉우리의 FWHM 값은 33 nm로 매우 좁게 나타났다.

Fabrication and Characterization of Free-Standing DBR Porous Silicon Film

  • Um, Sungyong;Sohn, Honglae
    • 통합자연과학논문집
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    • 제7권1호
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    • pp.1-4
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    • 2014
  • Distributed Bragg reflector porous silicon of different characteristics were formed to determine their optical constants in the visible wavelength range using a periodic square wave current between low and high current densities. The surface and cross-sectional SEM images of distributed Bragg reflector porous silicon were obtained using a cold field emission scanning electron microscope. The surface image of distributed Bragg reflector porous silicon indicates that the distributions of pores are even. The cross-sectional image illustrates that the multilayer of distributed Bragg reflector porous silicon exhibits a depth of few microns and applying of square current density during the etching process results two distinct refractive indices in the contrast. Distributed Bragg reflector porous silicon exhibited a porosity depth profile that related directly to the current-time profile used in etch. Its free-standing film was obtained by applying an electro-polishing current.

2 GHz 대역 RF 대역통과 필터 응용을 위한 AlN 압전 박막을 이용한 FBAR 소자 (FBAR Device with Thin AlN Piezoelectric Film for 2 GHz RF Bandpass Filter Applications)

  • Giwan Yoon;Munhyuk Yim;Dongkyu Chai;Kim, Sanghee;Kim, Jongheon
    • 한국정보통신학회논문지
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    • 제7권2호
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    • pp.250-254
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    • 2003
  • 본 논문에서는 2GHz 대역 RF 대역통과 필터 응용을 위한 FBAR 소자에 대한 연구를 발표한다. 본 연구의 FBAR 소자는 크게 상부 및 하부 전극 사이에 압전체(AlN)가 삽입되어 있는 공진부와 SiO2/W이 여러층으로 적층되어 있는 음향반사층 두 부분으로 구성되어 있다. RF sputtering 방법으로 증착된 AlN 박막은 c축이 기판에 수직한 정도가 우수한 c축 우선 배향성을 갖는다. 이때 결정립(grain)은 길고 얇은 주상형(columnar)을 보인다. 뿐만아니라, 우수한 품질계수(4300)와 반사손실(37.19 dB)도 얻어졌다.

Analysis on Design and Fabrication of High-diffraction-efficiency Multilayer Dielectric Gratings

  • Cho, Hyun-Ju;Lee, Kwang-Hyun;Kim, Sang-In;Lee, Jung-Hwan;Kim, Hyun-Tae;Kim, Won-Sik;Kim, Dong Hwan;Lee, Yong-Soo;Kim, Seoyoung;Kim, Tae Young;Hwangbo, Chang Kwon
    • Current Optics and Photonics
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    • 제2권2호
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    • pp.125-133
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    • 2018
  • We report an in-depth analysis of the design and fabrication of multilayer dielectric (MLD) diffraction gratings for spectral beam combining at a wavelength of 1055 nm. The design involves a near-Littrow grating and a modal analysis for high diffraction efficiency. A range of wavelengths, grating periods, and angles of incidence were examined for the near-Littrow grating, for the $0^{th}$ and $-1^{st}$ diffraction orders only. A modal method was then used to investigate the effect of the duty cycle on the effective indices of the grating modes, and the depth of the grating was determined for only the $-1^{st}$-order diffraction. The design parameters of the grating and the matching layer thickness between grating and MLD reflector were refined for high diffraction efficiency, using the finite-difference time-domain (FDTD) method. A high reflector was deposited by electron-beam evaporation, and a grating structure was fabricated by photolithography and reactive-ion etching. The diffraction efficiency and laser-induced damage threshold of the fabricated MLD diffraction gratings were measured, and the diffraction efficiency was compared with the design's value.

고 안정화 프로터결정 실리콘 다층막 태양전지 (Highly Stabilized Protocrystalline Silicon Multilayer Solar Cells)

  • 임굉수;곽중환;권성원;명승엽
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2005년도 춘계학술대회
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    • pp.102-108
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    • 2005
  • We have developed highly stabilized (p-i-n)-type protocrystalline silicon (pc-Si:H) multilayer solar cells. To achieve a high conversion efficiency, we applied a double-layer p-type amorphous silicon-carbon alloy $(p-a-Si_{1-x}C_x:H)$ structure to the pc-Si:H multilayer solar cells. The less pronounced initial short wavelength quantum efficiency variation as a function of bias voltage proves that the double $(p-a-Si_{1-x}C_x:H)$ layer structure successfully reduces recombination at the p/i interface. It was found that a natural hydrogen treatment involving an etch of the defective undiluted p-a-SiC:H window layer before the hydrogen-diluted p-a-SiC:H buffer layer deposition and an improvement of the order in the window layer. Thus, we achieved a highly stabilized efficiency of $9.0\%$ without any back reflector.

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관통형 비아가 있는 다층 PCB의 SI 성능 연구 (Study of SI Characteristic of Multilayer PCB with a Through-Hole Via)

  • 김리진;이재현
    • 한국전자파학회논문지
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    • 제21권2호
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    • pp.188-193
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    • 2010
  • 본 논문은 관통형 비아와 전송 선로 사이의 임피던스 불연속과 P/G(Power/Ground) 면 사이에서 발생되는 공진으로 인한 클록 신호 응답 성능 저하가 관통형 비아(through-hole via)가 있는 4층 PCB(Printed Circuit Boards)의 SI(Signal Integrity) 성능에 악영향을 미치는 것을 이론적으로 분석하였다. 비아 구조의 집중소자 모델링을 이용한 반사 전압 계산과 TDR(Time Domain Reflector) 시뮬레이션 결과 비교로 관통형 비아와 전송 선로 사이의 임피던스 불연속 최소화 시킬 수 있고, 관통형 비아 위치를 이용한 P/G면 공진 상쇄의 시뮬레이션 결과로 클록 신호 응답 성능을 향상시킬 수 있음을 확인하였다.

Realization of FBAR Devices for Broadband WiMAX Applications

  • Mai, Linh;Lee, Jae-Young;Pham, Van Su;Yoon, Gi-Wan
    • Journal of information and communication convergence engineering
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    • 제6권1호
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    • pp.34-37
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    • 2008
  • Effects of the addition of Cr adhesion layer to $W/SiO_2$ multilayer Bragg reflectors on the resonance characteristics of film bulk acoustic wave resonator (FBAR) devices are presented. Main resonance peaks could be significantly shifted to higher frequency, mainly due to the addition of Cr adhesion layer to multilayer Bragg reflectors and control of the bottom electrode thickness as well. The FBAR devices with the Cr adhesion layer in Bragg reflectors could result in much more improved resonance characteristics at about 3 GHz in terms of return loss and Q-factor.

이산화탄소 감지를 위한 4.26 ㎛ 필터용 poly-Si/SiO2 다층 박막 기반의 패브리 페로-필터 (Si/SiO2 Multilayer-based Fabry-Perot Filter for 4.26 ㎛ Filtering in Carbon Dioxide Detection)

  • 도남곤;이준엽;정동건;공성호;정대웅
    • 센서학회지
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    • 제30권1호
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    • pp.56-60
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    • 2021
  • In this study, the relationship between the transmitted light intensity and full-width-at-half-maximum (FWHM) of a Fabry-Perot filter was investigated. The measured refractive indices and absorption coefficients of the fabricated thin films were applied to the Fabry-Perot filter via simulations using optical software. Although considerable research has been conducted on Fabry-Perot filters, this study focused on the usefulness of 4.26-㎛ infrared filtering in carbon dioxide detection. Optical analysis was performed considering the effects of the thickness, refractive indices, and number of thin films in a distributed Bragg reflector. Ultimately, a clear trade-off relationship was observed wherein the transmitted light intensity decreased as the number of multilayers increased; however, the FWHM was observed to be narrower.

A New Technique to Improve ZnO-based FBAR Device Performances

  • Mai, Linh;Lee, Jae-Young;Pham, Van Su;Yoon, Gi-Wan
    • 한국정보통신학회:학술대회논문집
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    • 한국해양정보통신학회 2007년도 춘계종합학술대회
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    • pp.437-440
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    • 2007
  • This paper presents the improvement of the resonance characteristics of film bulk acoustic-wave resonator (FBAR) devices fabricated on multilayer Bragg reflectors (BRs) based on inserting ultra-thin chromium (Cr) adhesion layers into BRs and post-annealing processes. The measurements show excellent improvement of return loss $(S_{11})$ and Q-factor by the combined use of Cr adhesion layers and thermal treatments particularly for 120 minutes at $200^{\circ}C$.

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A Method to Improve Bragg Reflectors Quality in FBAR Devices

  • Mai, Linh;Lee, Jae-Young;Pham, Van Su;Yoon, Gi-Wan
    • Journal of information and communication convergence engineering
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    • 제5권4호
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    • pp.316-319
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    • 2007
  • This paper presents some methods to improve the resonance characteristics of film bulk acoustic-wave resonator (FBAR) devices. The FBAR devices were fabricated on multilayer Bragg reflectors (BR) into which very thin chromium (Cr) adhesion layers were inserted, followed by several kinds of thermal annealing processes. These methods resulted in an excellent device improvement in terms of return loss and Q-factors.