Kun Ho Kim

Structural, electrical and optical properties of aluminum doped zinc oxide films prepared by radio frequency magnetron sputtering

Aluminum doped zinc oxide (AZO) films are prepared by rf magnetron sputtering on glass or Si substrates using specifically designed ZnO targets containing different amount of Al2O3 powder as the Al doping source. The structural, electrical, and optical properties of the AZO films are investigated in terms of the preparation conditions, such as the Al2O3 content in the target, rf power, substrate temperature and working pressure. The crystal structure of the AZO films is hexagonal wurtzite. The orientation, regardless of the Al content, is along the c axis perpendicular to the substrate. The doping concentration in the film is 1.9 at. % for 1 wt % Al2O3 target, 4.0 at. % for 3 wt % Al2O3 target, and 6.2 at. % for 5 wt % Al2O3 target. The resistivity of the AZO film prepared with the 3 wt % Al2O3 target is ∼4.7×10−4 Ω cm, and depends mainly on the carrier concentration. The optical transmittance of a 1500-A-thick film at 550 nm is ∼90%. The optical band gap depends on the Al doping level and on the microstr...

The physical properties of Al-doped zinc oxide films prepared by RF magnetron sputtering

Al-doped zinc oxide (AZO) films are prepared by RF magnetron sputtering on glass and Si substrates with specifically designed ZnO targets containing different amounts of Al2O3 powder as a doping source. The physical properties of the AZO films are investigated in terms of the preparation conditions, such as Al2O3 content in the target, RF power (PRF), substrate temperature (Ts) and working pressure (Pw). The crystal structure of the AZO film is hexagonal wurtzite, and all the films show the typical crystallographic orientation, with the c-axis perpendicular to the substrate. The growth rate increases with increasing PRF, but decreases with increasing Ts and Pw. Films 1500 A thick with the lowest resistivity (ρ of 4.7 × 10−4 ω cm and the transmittance over 90% at the visible region are prepared by using norminal 3 wt.% Al2O3 target at Ts = 150°C, Pw = 2 mTorr and PRF = 150 W. Optical transmittance measurements show that AZO films are degenerate semiconductors with direct bandgap. The optical energy bandgap for undoped ZnO film is ∼ 3.3 eV and those for AZO films increase as the carrier concentration (ne) in the film increases. The blue shift in the AZO films is proportional to one third power of ne.

Electronic structure of Zn1−xCoxO using photoemission and x-ray absorption spectroscopy

Electronic structures of homogeneous bulk samples of Zn0.9Co0.1O which do not exhibit diluted ferromagnetic semiconducting (DMS) behavior have been investigated using photoemission spectroscopy and x-ray absorption spectroscopy. We have found that the Co ions in Zn1−xCoxO are in the divalent Co2+(d7) states under the tetrahedral symmetry. Our finding indicates that the DMS properties will not be produced when Co ions are properly substituted for Zn sites, implying that the DMS properties observed in Zn1−xCoxO thin films are likely to be extrinsic.

Bulk-sensitive photoemission spectroscopy of A 2 FeMoO 6 double perovskites ( A = Sr , Ba )

The electronic structures of

The Burstein-Moss effect in Cu2GeSe3:Co2+ single crystals

{\mathrm{Sr}}_{2}{\mathrm{FeMoO}}_{6}

Growth of epitaxial C54 TiSi2 on Si(111) substrate by in situ annealing in ultrahigh vacuum

(SFMO) and

Resonant photoemission spectroscopy study of impurity-induced melting in Cr- and Ru-dopedNd1/2A1/2MnO3(A=Ca,Sr)

{\mathrm{Ba}}_{2}{\mathrm{FeMoO}}_{6}

In situ solid phase epitaxial growth of C49‐TiSi2 on Si (111)‐7×7 substrate

(BFMO) double perovskites have been investigated using Fe

Formation and characterization of the fluorocarbonated-SiO2 films by O2/FTES-helicon plasma chemical vapor deposition

2\stackrel{\ensuremath{\rightarrow}}{p}3d

Scanning photoelectron microscopy study of Ge1−xTx (T=Cr, Fe) diluted ferromagnetic semiconductor single crystals

resonant photoemission spectroscopy (PES) and the Cooper minimum in the Mo