원리 및 기능
공동기기원에 새롭게 도입된 ESCA 장비는 영국 Kratos사의 Axis Supra™이며 XPS (X-ray Photoelectron Spectrometer), UPS(Ultraviolet photoelectron spectroscopy), ISS(LEIS, Low energy Ion Scattering spectroscopy)로 구성되어 있다.
X-선 광전자 분광법(XPS)은 내각전자의 결합에너지를 측정함으로써 원소의 조성 및 화학 결합 상태에 대한 정보를 제공한다. 스펙트럼 분석 뿐 아니라 이미지 분석도 가능하여 표면의 화학조성에 대한 mapping이 가능하다. 복합 재료 및 고분자 시료의 Depth Profile 실험을 위하여 일반적인 Ar source 외에 GCIS(Gas Cluster Ion Source)를 구비하였다. 자외선 광전자 분광법(UPS)은 최외각 전자의 에너지를 측정함으로써 재료의 일함수에 대한 정보를 제공하며, 저에너지 이온 산란 분광법 (ISS)은 에너지 비율(입사 광선과 산란 광선의 운동에너지 사이의 비율)의 함수로 산란 이온의 강도를 기록함으로써 원소 조성 및 고체 표면의 구조에 대한 정보를 알 수 있다.
● 장비의 구성 및 기능
(1) XPS : 내각 전자의 결합에너지 분석, 화학결합 상태, 상대 정량
(2) UPS : 최외각 전자의 에너지 분석, band gap energy, work function
(3) AR-XPS : 각도 변환에 따른 광전자 분석법
(4) GCIS : 고분자 및 복합재료의 Depth Profile 실험
(5) ISS : 표면의 최상층에 대한 정보
기기활용
사양
1. Vacuum System
(1) The sample analysis chamber is a multiport ultra-high vacuum chamber of mu-metal construction.
(2) Bakeout : 24hour~7day timer with thermostatically controlled, no need remove any cables and cameras before baking.
(3) Pumping kit
- The sample analysis chamber : TMP, TSP
( Base pressure in the analysis chamber is < 5x10 –10 torr )
- The load lock chamber : TMP, oil free dry scroll pump.
( Base pressure in the analysis chamber is < 5x10-8 torr )
2. Electron energy analyser
(1) 165mm mean radius concentric hemispherical analyser for spectroscopy and a spherical mirror analyser for imaging.
(2) 128 channel delay line detector (DLD) be used for both spectroscopy and parallel imaging modes.
(3) In spectroscopy mode should have greater than 100 discrete data channels improving the sensitivity in spectroscopy mode.
(4) X-ray photoelectron spectroscopy
- Ultimate energy resolution : ≤ 0.48eV(Ag3d5/2 peak)
(5) X-ray photoelectron imaging
- Lateral resolution of the parallel imaging : ≤1㎛
3. Automated monochromatic X-ray source
(1) 500 mm Rowland circle geometry, controlled by data system.
(2) Auto arrangement provides easy control, optimisation and calibration of the mirror position and ensures that the X-ray illuminated area is correctly aligned with the analysis position.
4. Sample alignment system
(1) Load lock chamber camera gives a global view of each sample holder such that analysis positions can be viewed, indexed and pre-programmed ready for data acquisition.
(2) High magnification sample analysis chamber microscope has a motorized, more than 12 x optical zoom controlled from the data-system facilitating remote operation of the camera.
(3) The optical images are captured within the Data Acquisition software and should be saved and manipulated in the Data Processing software.
5. Sample manipulator and platen
(1) Automated five axis X,Y,Z,Ɵ,Φ precision manipulator system
X-axis ; 150 mm
Y-axis ; ±15 mm
Z-axis ; -12~+16 mm
θ-rotation ; ±90°
Φ-rotation ; ±180°
(2) The sample manipulator have standard reference materials (Au, Ag and Cu) for spectroscopic calibration as well as an Au grid for imaging calibration permanently mounted.
(3) sample holder : Dual height sample holder, Combination sample holder, Z-rotation sample holder
6. Gas cluster ion source
(1) Monatomic Ar+ ion mode : 500eV ~ 5keV
(2) Arn+ cluster ion mode : ~ 20keV
(3) The ion source be fully integrated with the data acquisition system.
7. UPS (Ultraviolet Photoelectron Spectroscopy)
(1) Windowless discharge lamp of fully bakeable metal and ceramic construction
(2) The minimum step size : 1 meV
(3) Sensitivity : 1,000,000 cps at 120 meV resolution
- Ag Fermi edge excited by He I radiation
(4) He I : He II ratio : 4 : 1
8. ISS (Ion Scattering Spectroscopy)
(1) Ion scattering spectroscopy : Ar+ or He+ ions.
(2) Energy resolution
Sensitivity : 12,000 cps/nA at 12eV FWHM
- Au scattering, 1 kV He+ ions