High quality polycrystalline bilayers of aluminium doped ZnO (Al:ZnO) were successively electrodeposited in the form of columnar structures preferentially oriented along the $\left(10\overline{1}1\right)$ crystallographic direction from aqueous solution of zinc nitrate (Zn(NO₃)₂) at negative electrochemical potential of E_C = (−0.8)–(−1.2) V and moderate temperature of 80 °C on gallium rich (30% Ga) chalcopyrite selenide Cu(In,Ga)Se₂ (CIGS) with chemically deposited ZnSe buffer (ZnSe/Cu(In,Ga)Se₂/Mo/glass). The aluminium doped ZnO layer properties have initially been probed by deposition of Al:ZnO/i-ZnO bilayers directly on Mo/glass substrates. The band-gap energy of the Al:ZnO/i-ZnO reference layers was found to vary from 3.2 to 3.7 eV by varying the AlCl₃ solute dopant concentration from 1 to 20 mM. The electrical resistivity of indium-pellet contacted highly doped Al:ZnO sheet of In/Al:ZnO/i-ZnO/Mo/glass reference samples was of the order ρ ~10⁻⁵ Ω·cm; the respective carrier concentration of the order 10²² cm⁻³ is commensurate with that of sputtered Al:ZnO layers. For crystal quality optimization of the bilayers by maintenance of the volatile selenium content of the chalcopyrite, they were subjected to 2-step annealing under successive temperature raise and N₂ flux regulation. The hydrostatic compressive strain due to Al³⁺ incorporation in the ZnO lattice of bilayers processed successively with 5 and 12 mM AlCl₃ dopant was ε_h = −0.046 and the respective stress σ_h = −20 GPa. The surface reflectivity of maximum 5% over the scanned region of 180–900 nm and the (optical) band gap of E_g = 3.67 eV were indicative of the high optical quality of the electrochemically deposited (ECD) Al:ZnO bilayers.

In this paper the internal electric fields of nearly lattice matched InAlN/GaN heterostructures were determined. Pin -diodes containing InAlN/GaN heterostructures grown on sapphire substrates by metalorganic vapour phase epitaxy were fabricated by standard lithography and metallization techniques. To determine the polarization fields in the InAlN quantum wells capacitance-voltage-measurements were performed on the pin -diodes. To reduce the measurement error, the heterostructure thicknesses were accurately determined by transmission electron microscopy. Large polarization fields, which correspond mainly to the spontaneous polarizations, for In _0.15 Al _0.85 N ( MV cm ⁻¹ ), In _0.18 Al _0.82 N ( MV cm ⁻¹ ) and In _0.21 Al _0.79 N ( MV cm ⁻¹ ) quantum wells were observed. The results of the internal field strength and field direction are in excellent agreement with values predicted by theory and a CVM-based coupled Poisson/carrier transport simulation approach.

Due to changes in the spontaneous and piezoelectric polarization, AlGaN/GaN heterostructures exhibit strong polarization fields at heterointerfaces. For quantum wells, the polarization fields lead to a strong band bending and a redshift of the emission wavelength, known as quantum-confined Stark effect. In this paper the polarization fields of thin AlGaN layers in a GaN matrix were determined by evaluating the changes in the depletion region width in comparison to a reference sample without heterostructure using capacitance–voltage-measurements. The polarization fields for Al_0.09Ga_0.91N (0.6 ± 0.7 MV cm⁻¹), Al_0.26Ga_0.74N (2.3 ± 0.6 MV cm⁻¹), Al_0.34Ga_0.66N (3.1 ± 0.6 MV cm⁻¹), Al_0.41Ga_0.59N (4.0 ± 0.7 MV cm⁻¹) and Al_0.47Ga_0.53N (5.0 ± 0.8 MV cm⁻¹) heterostructures were determined. The results of the field strength and field direction of all samples are in excellent agreement with values predicted by theory and a capacitance–voltage based Poisson-carrier transport simulation approach giving experimental evidence for a nonlinear increasing polarization field with Al-concentration.

An application of the ability of the Haar wavelet operational matrix to perform the numerical inverse Laplace transform as combined with the intrinsically convenient Haar wavelet transform of any time-domain signal is presented in this paper. A case study of the transient-and steady-state behavior of the input impedance of a short-circuited transmission line showcases a method to perform the numerical inverse Laplace transform of fractional-order approximative expressions of the skin effect. Furthermore, an improved skin effect approximation is presented.