| 1. |
- Fors, Rickard, et al.
(författare)
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Comparison of Sol-Gel Derived and Pulsed Laser Deposited Epitaxial La0.67Ca0.33MnO3 Films for IR Bolometer
- 2004
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Ingår i: Mat. Res. Soc. Symp. Proc.. - : Springer Science and Business Media LLC. ; 811, s. E2.5.1-E2.5.6, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial La0.67Ca0.33MnO3 films have been prepared on LaA1O3 crystals by pulsed laser deposition (PLD) and by a novel all-alkoxide sol-gel technique. Different out-of-plane lattice parameters are found for the as-prepared films, and scanning electron microscopy shows a more porous structure for sol-gel films as compared to PLD films. These differences are largely removed by post-annealing at 1000 °C. Transport measurements show maximum temperature coefficient of resistivity of 8.2 % K-1 at 258 K (PLD) and 6.1 % K-1 at 241 K (sol-gel) and :colossal magnetoresistance at 7 kOe of 35 % at 263 K (PLD) and 32 % at 246 K (sol-gel).
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| 2. |
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| 3. |
- Grishin, Alexander, et al.
(författare)
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Electro-optical properties of Na0.5K0.5NbO3 films on Si by free-space coupling technique
- 2004
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Ingår i: New Materials For Microphotonics. - : Springer Science and Business Media LLC. - 1558997679 ; , s. 225-229
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Konferensbidrag (refereegranskat)abstract
- We report electro-optic performance of highly polar axis oriented Na0.5K0.5NbO3 (NKN) films grown directly on Pt(100nm)/Ti(10nm)/SiO2/Si(001) substrates by rf-magnetron sputtering. Semitransparent gold electrodes (diameter circle divide = 2 mm) were deposited ontop the NKN films by a thermal evaporation through the contact mask. Processing parameters have been specially optimized to obtain "electrosoft" NKN films with a non-linear fatigue-free P-E characteristics: low remnant P-r = 3.6 muC/cm(2) and high induced polarization P = 26 muC/cm(2) @ 522 kV/cm, and the coercive field E-c = 39 kV/cm. Electro-optical characterization of NKN/Pt/Si films has been performed using waveguide refractometry: a free-space coupling of a light beam into the thin-film waveguide modes. Intensity of TM- and TE-polarized light of 670 nm laser diode reflected from the free surface of NKN film and Au-cladding NKN/PL/Si waveguide was recorded at zero and 30 V (100 kV/cm) bias electric field. Extraordinary and ordinary refractive indices as well as electro-optic coefficient have been determined by fitting these experimental data to the Fresnel formulas. Applying 160 V (530 kV/cm) across the parallel plate NKN capacitor (circle divide = 2 mm, thickness 3 mum), modulation of the reflected light as high as 40% was achieved.
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| 4. |
- Grishin, Alexander, et al.
(författare)
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Enhanced photoluminescence in [Er2O3/TiO2]m photonic crystals
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:11, s. 113122-
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Tidskriftsartikel (refereegranskat)abstract
- We survey optical properties of [Er2O3/TiO 2]6/Er2O32/[TiO 2/Er2O3]6 photonic crystals (PCs) pulsed laser deposited on to the glass substrates. The dispersion relations of refractive indexes and extinction coefficients of the constituent materials were obtained from the comparison of experimental and simulated transmission spectra of single layer Er2O3 and TiO2 reference films. Based on these data several PCs have been designed and grown to match stop band and cavity mode resonance at wavelengths close to the 523 nm Er 3+-ion Fraunhofer 4S3/2 absorption line. Precise control of chemical composition and uniform multilayer thickness enable achievement of superior optical performance of sintered PCs. Obtained dispersion relations were combined with the 2×2 transfer matrix formalism to compute PC transmittance that appeared to be in a good agreement with the experimental spectra. Pumping PCs with 514 nm light source we observed a strong photoluminescence (PL) at 1535 nm. In PC specially designed for the resonance wavelength λres =514 nm, C-band PL intensity experiences fivefold enhancement compared to a single layer Er2 O3 film of equivalent thickness.
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| 5. |
- Grishin, Alexander M., et al.
(författare)
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Luminescence in epitaxial Er-doped LiNbO3 films
- 2012
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 37:3, s. 419-421
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial Er-doped LiNbO3 films were pulsed-laser-deposited onto c-cut sapphire. Wavelength dispersion of the refractive index and the extinction coefficient was obtained by fitting the experimental transmittance spectrum to the Swanepoel formula and microscopic theory, which accounts for two resonance transitions in the electric dipole approximation. Strong room temperature luminescence was observed under 514.5 nm Ar-laser pumping. Two-lifetime (3.0 and 6.0 ms) luminescent decay is characteristic for the lasing I-4(13/2) -> I-4(15/2) transition in Er:LiNbO3 films.
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| 6. |
- Grishin, Alexander M., et al.
(författare)
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Optical dispersion and temperature dependent latching-type magneto-optical properties of magnetron sputtered Bi3Fe3.34Ga1.66O12 (001) and (111) films
- 2020
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Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 699
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Tidskriftsartikel (refereegranskat)abstract
- We report on optical dispersion and temperature dependence of latching-type magneto-optical properties of heavily Ga-doped bismuth iron garnet films rf-magnetron sputtered onto Gd3Ga5O12 (001) and (111) substrates. At lambda = 677 nm and room temperature, epitaxial Bi3Fe3.34Ga1.66O12 (001) and (111) films show, respectively, saturation Faraday rotation theta(Fsat) = - 0.92 x 10(4) and - 1.05 x 10(4) deg/cm, transmittance T = 0.86 and 0.81, magnetic hysteresis theta(F)-H loop squareness theta(Frem)/theta(Fsat) = 0.84 and 1.0, and coercive field H-c = 6.76 and 24.03 kA/m. Film's Faraday rotation is nicely fitted by molecular field Neel theory in the whole temperature range from T-C = 316 K down to 85 K where theta(Fsat) = - 1.9 x 10(4) deg/cm and H-c = 151.20 kA/m.
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| 7. |
- Grishin, Alexander M., et al.
(författare)
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Waveguiding in All-Garnet Heteroepitaxial Magneto-Optical Photonic Crystals
- 2019
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Ingår i: JETP Letters. - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0021-3640 .- 1090-6487. ; 109:2, s. 83-86
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Tidskriftsartikel (refereegranskat)abstract
- We report the properties of 1D all-garnet heteroepitaxial 21 layered magneto-optical photonic crystal designed and fabricated for the resonance wavelength 750 +/- 3 nm. It is composed of alternating magnetooptical-active Bi3Fe5O12 and transparent Sm3Ga5O12 quarter-wavelength layers radio frequency magnetron sputtered onto single crystalline Ca, Mg, Zr:Gd3Ga5O12(111) substrate. Edges of the band gap and resonant central peaks in transmission and Faraday rotation spectra experience significant (about 60 nm) "blueshift" when the angle of light incidence increases up to 70 degrees. Lower reflectance and strong enhancement of Faraday rotation of TE mode compared to the TM-polarized light testify a waveguiding of TE-mode within a resonant lambda/2 Bi3Fe5O12 cavity.
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| 8. |
- Grishin, Alexander, et al.
(författare)
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Processing and on-wafer measurements of ferroelectric interdigitated tunable microwave capacitors
- 2004
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Ingår i: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions. - : Springer Science and Business Media LLC. - 155899761X ; , s. 307-312
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Konferensbidrag (refereegranskat)abstract
- Na0.5K0.5NbO3 (NKN) and Pb(Zr0.53Ti0.47)O-3 (PZT) films have been grown by rf-magnetron sputtering and pulsed laser deposition techniques, correspondingly, on sapphire (Al2O3-0112, r-cut), YAlO3 + 1% Nd (Nd:YAlPO3-001), and quartz (Y+36degrees-cut) single crystal substrates. Interdigital capacitor (IDC) of coplanar waveguide (CPW) structures were defined by a standard lift off technique in a Au(0.5mum)/Cr(10nm) electrode electron beam evaporated on ferroelectric film surface. IDCs consisted of five pairs of fingers separated by 2 and 4 mum gap. On-wafer microwave characterization was performed using a workbench equipped with a coplanar probe station (Cascade Microtech) with G-S-G (Ground-Signal-Ground) Picoprobe, a network analyzer (Agilent Technologies E8364A) operating in 45 MHz to 40 GHz range and programmable power supply for de DUT (Device Under Test) biasing. Assumed equivalent circuit for the IDC/CPW structure contains planar capacitor under test C, the coplanar line with a complex impedance sigma and a parasitic capacitance C, between the signal and ground lines. The de-embedding technique has been employed to determine all six complex parameters C, sigma and C-p from S-parameter measurements performed for three different device structures: device, open and thru. NKN film interdigital capacitors on sapphire show superior performance in this microwave range: the frequency dispersion was as low as 18%, voltage tunability = 1 - C(40V)/C(0) (40 V, 200 kV/cm) about 14%, loss tangent similar to0.11, K-factor = tunability/tandelta from 131% @ 10 GHz: to 56% @ 40 GHz. The reliability of the de-embedding procedure is clearly proved by analysis of the frequency dependences of the parasitic capacitance and loss tangent as well as impedance of the coplanar line. Within the accuracy of experimental data and de-embedding calculations these values appear to be voltage independent: C-p similar to 70 fF, tan delta(p) changes from 0.07 @ 10 GHz to 0.15 @ 40 GHz; real and imaginary part of interconnect impedance increases with frequency from 0.16 Omega @ 10 GHz to 0.36 Omega @ 40 GHz and from 1.6 Omega @ 10 GHz to 5.84 Omega @ 40 GHz respectively.
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| 9. |
- Jalali-Roudsar, Amir A., et al.
(författare)
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Microwave and magneto-optic properties of pulsed laser deposited bismuth iron garnet films
- 2001
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Ingår i: IEEE transactions on magnetics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9464 .- 1941-0069. ; 37:4, s. 2454-2456
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Tidskriftsartikel (refereegranskat)abstract
- We report on processing and comparative characterization of epitaxial Bi3Fe5O12 (BIG) films grown by pulsed laser ablation of a precursor oxide target onto (NdGd)(3)(ScGa)(5)O-12 [NGSGG(111)] and Gd-3 (ScGa)(5)O-12 (GSGG(001)] single crystals. Comprehensive X-ray diffraction analyses reveal the epitaxial quality of the BIG films: they are single phase, exclusively (111) and (001) oriented with less than 0.4 degrees and 0.06 degrees of the full width at half maximum of the rocking curve of main texture Bragg reflection [(111) for NGSGG and (001) for GSGG substrate, respectively]. The films are strongly in-plane textured with cube-on-cube film-to-substrate epitaxial relationship. VSM and ferromagnetic resonance measurements revealed in-plane magnetization in BIG/GSGG(001) film, while the BIG/NGSGG(111) film was found to have perpendicular magnetization. For BIG(001) and (111) films the saturation magnetization 4 piM(s) was found to be 1400 and 1200 Gs; the Faraday rotation at 635 nm was -7.8 and -6.7 deg/mum; the constant of uniaxial magnetic anisotropy was K-u* = -8.70 X 10(4) and +1.16 x 10(4) erg/cm(3); the constant of cubic magnetic anisotropy K-1 = -3.6 x 10(3) and -7.14 x 10(3) erg/cm(3). High Faraday rotation and low coercive field (less than or equal to 40 Oe) of BIG/GSGG(001) films show promise for their use in integrated magneto-optic applications.
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| 10. |
- Khartsev, Sergey, et al.
(författare)
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High‐Quality Si‐Doped β‐Ga 2 O 3 Films on Sapphire Fabricated by Pulsed Laser Deposition
- 2020
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 258:2, s. 2000362-2000362
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed laser ablation is used to form high-quality silicon-doped β-Ga2O3 films on sapphire by alternatively depositing Ga2O3 and Si from two separate sources. X-ray analysis reveals a single crystallinity with a full width at half maximum for the rocking curve around the (−201) reflection peak of 1.6°. Silicon doping concentration is determined by elastic recoil detection analysis (ERDA), and the best electrical performance is reached at a Si concentration of about 1 × 1020 cm−3, using optimized deposition parameters. It is found that a high crystalline quality and a mobility of about 2.9 cm2 (V s)−1 can be achieved by depositing Si and Ga2O3 from two separate sources. Two types of Schottky contacts are fabricated: one with a pure Pt and one with a PtOx composition. Electrical results from these structures are also presented.
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