Jun Seok Byun

Dielectric response of AlSb from 0.7 to 5.0 eV determined by in situ ellipsometry

We present pseudodielectric function data ⟨e⟩=⟨e1⟩+i⟨e2⟩ from 0.7 to 5.0 eV of oxide-free AlSb that are the closest representation to date of the intrinsic bulk dielectric response e of the material. Measurements were done on a 1.5 μm thick film grown on (001) GaAs by molecular beam epitaxy. Data were obtained with the film in situ to avoid oxidation artifacts. Overlapping critical-point (CP) structures in the E2 energy region were identified by means of band-structure calculations done with the linear augmented Slater-type orbital method. Calculated CP energies agree well with those obtained from data, confirming the validity of the calculations.

Optical properties of InxAl1−xAs alloy films

Pseudodielectric functions ⟨e⟩ of InxAl1−xAs ternary alloy films were determined from 1.5to6.0eV by spectroscopic ellipsometry. We minimized overlayer effects by performing wet-chemical etching to more accurately determine intrinsic bulk dielectric responses. Energies of the E1, E1+Δ1, E0′, E2, E2+Δ2 and E2′ critical points (CPs) were identified by band structure calculations of the linear augmented Slater-type orbital method. These calculations also showed a crossing of the E0′ and E2 CP structures with increasing In composition and a new saddle point in the AlAs band structure.

Temperature dependence of the dielectric functions and the critical points of InSb by spectroscopic ellipsometry from 31 to 675 K

We report the complex dielectric function of InSb for temperatures from 31 to 675 K and energies from 0.74 to 6.42 eV. The spectra were obtained by rotating-compensator spectroscopic ellipsometry on bulk InSb. The critical point (CP) energies were determined using numerically calculated second energy derivatives of the data. At low temperature, the CP structures are blue-shifted and significantly sharpened relative to those seen at high temperature. The temperature dependence of the E1, E1+Δ1, E0′, Δ5cu-Δ5vu (0.35, 0, 0), E0′+Δ0′, Δ5cl-Δ5vu (0.35, 0, 0), E2, E2′, E2+Δ2, E2′+Δ2, E1′, E1′+Δ1′, and E1′+Δ1′+Δ1 CPs was determined by fitting to a phenomenological expression that contains the Bose-Einstein statistical factor or to a linear equation. In particular, temperature dependences of CPs below 100 K and those of the E0′, E0′+Δ0′, E2′, E2+Δ2, E2′+Δ2, E1′+Δ1′, and E1′+Δ1′+Δ1 transitions have not previously been reported.

Temperature dependent dielectric function and the E0 critical points of hexagonal GaN from 30 to 690 K

The complex dielectric function ɛ and the E0 excitonic and band-edge critical-point structures of hexagonal GaN are reported for temperatures from 30 to 690 K and energies from 0.74 to 6.42 eV, obtained by rotating-compensator spectroscopic ellipsometry on a 1.9 μm thick GaN film deposited on a c-plane (0001) sapphire substrate by molecular beam epitaxy. Direct inversion and B-splines in a multilayer-structure calculation were used to extract the optical properties of the film from the measured pseudodielectric function ⟨ɛ⟩. At low temperature sharp E0 excitonic and critical-point interband transitions are separately observed. Their temperature dependences were determined by fitting the data to the empirical Varshni relation and the phenomenological expression that contains the Bose-Einstein statistical factor.

Parameterization of the dielectric function of InP from 1.19 to 6.57 eV for temperatures from 25 to 700 K

We present an analytic expression that accurately represents the dielectric function ɛ = ɛ1 + iɛ2 of InP from 1.19 to 6.57 eV for temperatures from 25 to 700 K. The original data were obtained on a InP substrate by spectroscopic ellipsometry. The analytic representation is based on the parametric model, which is known to accurately portray ɛ without unphysical assumptions. The ɛ data are successfully reconstructed by eight Gaussian-broadened polynomials and a pole and can be used to determine ɛ as a continuous function of energy and temperature within the limits given above. Our results should be useful in a number of contexts, including device design and in situ monitoring of deposition. A representative deposition example is discussed.

Interband transitions and dielectric functions of InGaSb alloys

We report pseudodielectric functions of In1−xGaxSb ternary alloy films from 1.5 to 6.0 eV determined by spectroscopic ellipsometry. Artifacts were minimized by real-time assessment of overlayer removal, leading to accurate representations of the bulk dielectric responses of these materials. Critical-point (CP) energies were obtained from numerically calculated second energy derivatives, and their Brillouin-zone origins identified by band-structure calculations. The E2′ and E2 + Δ2 CP energies cross with increasing In content as a result of increasing spin-orbit splitting Δ2.

Nondestructive analysis of coated periodic nanostructures from optical data

Optical data are essential for the accurate nondestructive determination of profiles of periodic structures in integrated-circuit technology. In rigorous coupled-wave analysis, the sample is generally modeled as layers consisting of a single material and the ambient. We extend present capabilities to the analysis of structures with overlayers and demonstrate our approach by determining quantitatively the thicknesses of top, sidewall, and bottom oxides of deliberately and naturally oxidized structures.

Parametrization of the Optical Constants of AlAs x Sb 1-x Alloys in the Range 0.74-6.0 eV

We report parameters that allow the dielectric functions

Three-Dimensional Analysis of the Collapse of a Fatty Acid at Various Compression Rates using In Situ Imaging Ellipsometry

{\varepsilon}={\varepsilon}_1+i{\varepsilon}_2

Stability of UV exposed RR-P3BT films by spectroscopic ellipsometry

of