Correlation of real time spectroellipsometry and atomic force microscopy measurements of surface roughness on amorphous semiconductor thin films

Films of Ni x W 1Àx oxide with 0.05 x 0.53 were produced by reactive dc magnetron co-sputtering onto Si. Such films have documented electrochromism. Spectroscopic ellipsometry was used to extract accurate data on the dielectric function in the photon range 0.062 to 5.62 eV. The results for 0.62 to 5.62 eV were compared with computations from the Bruggeman effective medium theory applied to two nanostructural models: one representing a random mixture of structural entities characterized by the dielectric functions of WO 3 and NiWO 4 and the other describing a random mixture of WO 3 and NiO. Unambiguous evidence was found in favor of the former model, and hence the films are composed of nanosized tungsten oxide and nickel tungstate. This agrees excellently with an earlier investigation of ours on Ni x W 1Àx oxide films, where nanostructure was inferred from Raman spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction. V C 2012 American Institute of Physics. [http://dx

Section: B Datasupporting

confidence: 70%

Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory

Valyukh

Green

Granqvist

et al. 2012

“…From Table I, we observed that the void percentage increases with the sol concentration and saturated at 50% for sol of 0.12 M. This indicates that at low concentration the surface roughness is small so that the contribution is mainly due to pores while at high concentration the void percentage is mostly due to the surface roughness. Unlike the relation obtained in semiconductor, 14 an modified correlation of ellipsometry and AFM measurements of surface roughness was observed in our measurement:…”

Section: Resultscontrasting

confidence: 42%

Spectroellipsometric study of sol–gel derived potassium sodium strontium barium niobate films

Mak

Lai

Wong

et al. 2001

Investigation of dielectric and electrical properties of Mn doped sodium potassium niobate ceramic system using impedance spectroscopy J. Appl. Phys. 110, 104102 (2011) Determination of depolarization temperature of (Bi1/2Na1/2)TiO3-based lead-free piezoceramics J. Appl. Phys. 110, 094108 (2011) Finite element method simulation of the domain growth kinetics in single-crystal LiTaO3: Role of surface conductivity J. Appl. Phys. 110, 052016 (2011) Local domain engineering in relaxor 0.77PbMg1/3Nb2/3O3-0.23PbSc1/2Nb1/2O3 single crystals J. Appl. Phys. 110, 052002 (2011) Determination of the effective coercive field of ferroelectrics by piezoresponse force microscopy J. Appl. Phys. 110, 052012 (2011) Additional information on J. Appl. Phys. Spectroscopic ellipsometry ͑SE͒ was used to characterize the sol-gel derived ͑K 0.5 Na 0.5 ͒ 0.4 ͑Sr 0.6 Ba 0.4 ͒ 0.8 Nb 2 O 6 ͑KNSBN͒ thin films as a function of sol concentration. In the analysis of the measured SE spectra, a modified double-layer Forouhi-Bloomer model was adopted to represent the optical properties of the KNSBN films. In this model, the films were assumed to consist of two layers-a bottom bulk KNSBN layer and a surface layer that composed of bulk KNSBN as well as void. Good agreement was obtained between the measured spectra and the model calculations in the chosen spectral region. Effective medium approximation theory was used to evaluate the effective refractive index for the surface layer. The results of SE have been correlated with atomic force microscopy measurements of surface roughness. Our analyses have shown that the surface layer had a lower refractive index than the bottom one. In addition, the refractive index and the surface roughness of the KNSBN films increase with the sol concentration.

“…This justifies the two-layer model used for the analysis of ellipsometry data. It may be mentioned that Koh et al 72 have also…”

mentioning

confidence: 99%

Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

Biswas

Bhattacharyya

Sahoo

et al. 2008

Properties of InxGa1−xN films in terahertz range Appl. Phys. Lett. 100, 071913 (2012) Thermal carrier emission and nonradiative recombinations in nonpolar (Al,Ga)N/GaN quantum wells grown on bulk GaN J. Appl. Phys. 111, 033517 (2012) Surface depletion mediated control of inter-sub-band absorption in GaAs/AlAs semiconductor quantum well systems Appl. Phys. Lett. 100, 051110 (2012) High-Q optomechanical GaAs nanomembranes Appl. Phys. Lett. 99, 243102 (2011) Mg-induced terahertz transparency of indium nitride films Appl. Phys. Lett. 99, 232117 (2011) Additional information on J. Appl. Phys. GaN films have been deposited by reactive rf sputtering of GaAs target in 100% nitrogen ambient on quartz substrates at different substrate temperatures ranging from room temperature to 700°C. A series of films, from arsenic-rich amorphous to nearly arsenic-free polycrystalline hexagonal GaN, has been obtained. The films have been characterized by phase modulated spectroscopic ellipsometry to obtain the optical parameters, viz., fundamental band gap, refractive index, and extinction coefficient, and to understand their dependence on composition and microstructure. A generalized optical dispersion model has been used to carry out the ellipsometric analysis for amorphous and polycrystalline GaN films and the variation of the optical parameters of the films has been studied as a function of substrate temperature. The refractive index values of polycrystalline films with preferred orientation of crystallites are slightly higher ͑2.2͒ compared to those for amorphous and randomly oriented films. The dominantly amorphous GaN film shows a band gap of 3.47 eV, which decreases to 3.37 eV for the strongly c-axis oriented polycrystalline film due to the reduction in amorphous phase content with increase in substrate temperature.