Aluminum Zinc Oxide Thin Films Research Articles

Near-zero-index ultra-fast pulse characterization

Transparent conducting oxides exhibit giant optical nonlinearities in the near-infrared window where their linear index approaches zero. Despite the magnitude and speed of these nonlinearities, a “killer” optical application for these compounds has yet to be found. Because of the absorptive nature of the typically used intraband transitions, out-of-plane configurations with short optical paths should be considered. In this direction, we propose an alternative frequency-resolved optical gating scheme for the characterization of ultra-fast optical pulses that exploits near-zero-index aluminium zinc oxide thin films. Besides the technological advantages in terms of manufacturability and cost, our system outperforms commercial modules in key metrics, such as operational bandwidth, sensitivity, and robustness. The performance enhancement comes with the additional benefit of simultaneous self-phase-matched second and third harmonic generation. Because of the fundamental importance of novel methodologies to characterise ultra-fast events, our solution could be of fundamental use for numerous research labs and industries.

Analysis of flat glass deposited thin film made from aluminium doped zinc oxide (AZO)

Doped aluminium zinc oxide (Al doped ZnO/AZO) thin films that were synthesised on glass and nanostructured with cadmium substrates were allowed to degrade over a period of two years in a controlled environment. The films were placed in airtight containers for eighteen months and later placed in plastic containers for four months at room temperature. This environment was able to allow slight damping at times to accelerate the physical degradation process. The evolution of transparent conductive oxide (TCO) like aluminium doped zinc oxide (AZO) has been a welcome development in solar cell production. But it quickly deteriorates which is a drawback in its application. In this study, each film was doped with the same Al concentration but in different mediums such as cadmium, nitrogen, silver and argon (Cd, N2, Ag, Ar). To investigate the optical performance, the transmittance of each film was studied. An average transmittance of above 65 % was observed. The optical properties in these films were varied by the different mediums which are cadmium, nitrogen, silver and argon (Cd, N2, Ag, Ar). It was observed that the transmission over the visible range varied as the wavelength increased. This change happens because of free carriers coupling to the electric field leading to high reflection. Therefore, the simplest way to quantify the degree of degradation was to investigate the optical properties such as the transmission between layers. The micro-structure of these thin films were evaluated using scanning probe microscopy (SPM) to demonstrate degradation. Finally, the morphological and elemental compositions were analysed with scanning electron microscopy (SEM) and energydispersive X-ray spectroscopy (EDX).

Visible photon generation via four-wave mixing in near-infrared near-zero-index thin films.

Optical nonlinearities can be strongly enhanced by operating in the so-called near-zero-index (NZI) regime, where the real part of the refractive index of the system under investigation approaches zero. Here we experimentally demonstrate semi-degenerate four-wave mixing (FWM) in aluminum zinc oxide thin films generating radiation tunable in the visible spectral region, where the material is highly transparent. To this end, we employed an intense pump (787 nm) and a seed tunable in the NIR window (1100-1500 nm) to generate a visible idler wave (530-620 nm). Experiments show enhancement of the frequency conversion efficiency with a maximum of 2% and a signal-to-pump detuning of 360 nm. Effective idler wavelength tuning has also been demonstrated by operating on the temporal delay between the pump and signal.

Aluminium zinc oxide as a saturable absorber for passively Q-switched and mode-locked erbium-doped fiber laser

Transparent conductive oxides (TCOs) are widely integrated in the field of optoelectronics since they are optically transparent and electrically conductive at the same time. Indium tin oxide (ITO) is a well-developed TCO, but due to its high cost, aluminum zinc oxide (AZO) is now emerging as a promising low-cost replacement for ITO. This work reports on AZO thin film prepared with polyvinyl alcohol (PVA) as a host material. The AZO–PVA thin film was incorporated into an erbium-doped fiber laser (EDFL) as a saturable absorber for the first time. Both Q-switched and nanosecond pulse mode-locked operation were experimentally achieved. The Q-switched EDFL operated at the center wavelength of 1559.6 nm, which had the shortest pulse width of 2.2 µs, the maximum repetition rate of 86 kHz and the highest pulse energy of 47.3 nJ. The mode-locked was achieved at the center wavelength of 1560.4 nm.

The Effect of Annealing Temperature on Structural and Solid State Properties of Aluminium Zinc Oxide (AlZnO) Deposited by Chemical Bath technique

In this work, we studied the effect of annealing temperature on the structural and solid state properties of AlZnO thin films using Chemical bath deposition technique. The thin films grown was annealed at various temperatures of 100oC, 150oC to 200oC The morphological and structural properties were studied using XRD and SEM, while the optical properties were studied using UVVIS Spectroscopy from where the bad gap, dielectric constant, refractive index, extinction coefficient and optical conductivity were deduced from the theoretical equations.From the result, it is observed that there is effect of annealing temperature on these properties such that the grain size and x-ray characteristics depicted different characteristics at these various temperatures.

Effect of RF power of Al2O3 target on the physical properties of aluminum-doped zinc oxide films

In this report, we investigate the optical and electrical properties of aluminum zinc oxide (AZO) thin films using magnetron sputtering method in preparing the thin films and spectrophotometer to measure the optical characteristics. The X-ray diffraction (XRD) patterns of the films are found to have amorphous structure. The optical band gap Eg, refractive index n, electronic $${\alpha }_{\mathrm{Ep}}$$ polarizability, carrier concentration Nc, plasma frequency $${\omega }_{\mathrm{p}}$$ , electrical resistivity $${\rho }_{\mathrm{s}}$$ , and sheet resistance $${R}_{\mathrm{sh}}$$ are found to decrease with increasing the RF power of Al2O3 target. The refractive index shows a normal dispersion. Urbach energy Eu and figure of merit are found to increase with increasing the RF power of Al2O3 target. Our results manifest that the change of the RF power of the Al2O3 target can improve the AZO thin films, which is appropriate for solar sell applications.

Adiabatic frequency shifting in epsilon-near-zero materials: the role of group velocity

The conversion of a photon’s frequency has long been a key application area of nonlinear optics. It has been discussed how a slow temporal variation of a material’s refractive index can lead to the adiabatic frequency shift (AFS) of a pulse spectrum. Such a rigid spectral change has relevant technological implications, for example, in ultrafast signal processing. Here, we investigate the AFS process in epsilon-near-zero (ENZ) materials and show that the frequency shift can be achieved in a shorter length if operating in the vicinity of R e { ε r } = 0 . We also predict that, if the refractive index is induced by an intense optical pulse, the frequency shift is more efficient for a pump at the ENZ wavelength. Remarkably, we show that these effects are a consequence of the slow propagation speed of pulses at the ENZ wavelength. Our theoretical predictions are validated by experiments obtained for the AFS of optical pulses incident upon aluminum zinc oxide thin films at ENZ. Our results indicate that transparent metal oxides operating near the ENZ point are good candidates for future frequency conversion schemes.

Physical properties of indium zinc oxide and aluminium zinc oxide thin films deposited by radio-frequency magnetron sputtering

Indium-doped zinc oxide (IZO) and aluminium-doped zinc oxide (AZO) thin films were grown by radio-frequency (RF) magnetron sputtering onto optical glass substrates and their structural, morphological, and optical properties were discussed in terms of varying the sputtering power as 40 W, 60 W, 80 W, and 100 W. No heating substrate or any post-thermal treatment was performed. The structural features were analyzed by grazing incidence X-ray diffraction and revealed the amorphous phase for IZO samples, while the AZO thin films inherited the Wurtzite structure of zinc oxide. The morphological properties were investigated by atomic force microscopy (AFM), in tapping mode and scanning electron microscopy (SEM). The AFM images showed relatively uniform and smooth surfaces for all prepared structures. The optical transmission spectra proved the excellent theoretical values of transparency for metallic oxides in the visible region of the electromagnetic spectrum, i.e. ∼60% for IZO and ∼70% for AZO. The obtained results showed that even without any thermal treatment the structural, morphological, and optical properties of IZO and AZO thin films prepared by RF magnetron sputtering are similar with those for samples subjected to medium or high temperatures.

Analysis of Pr co-doped Al:ZnO thin films using feasible nebulizer spray technique for optoelectronic technology

The rare earth element, i.e., praseodymium (Pr) co-doped aluminium zinc oxide (AZO) thin films is coated on a well-cleaned glass substrate by facile and cost-effective nebulizer spray technique. The Pr co-doping concentrations varied from 0 to 1.5% with the AZO structure in the steps of 0.5%. The structural analysis was characterized by X-ray diffraction (XRD), showing that all the diffracted peaks exhibit polycrystalline hexagonal wurtzite structure and the size of the crystallites is abridged with increasing Pr doping level due to lattice defects. In Raman analysis, the existence of high mode peak E2 at 437 cm−1; confirmed ZnO wurtzite structure. From the morphological study, it is clearly visualized that the film possesses spherical shaped grains which were uniformly distributed without any pinholes and voids. The surface roughness of the films was increased considerably from 22 to 39 nm on growing Pr doping from 0 to 1.5% as seen using atomic force microscope. Energy dispersive X-ray analysis and elemental mapping images clearly showed the subsistence of Al, Zn, O and Pr elements in Pr:AZO film. The prepared films exposed good transmittance range between 84 and 90% and the optical band gap was found to be 3.28 eV for initial Pr (0.5%) doping concentration. The PL spectra clearly showed that a high intense emission peak observed at 390 nm are associated with NBE which indicates that the film has good optical quality. Hall measurement revealed that the prepared film, i.e., 1.5% Pr-doped AZO film has low resistivity and high carrier concentration which is perfectly suit for optoelectronic device applications.

Effect of Oxygen Flow Rate on Structural, Electrical and Optical Properties of Zinc Aluminum Oxide Thin Films Deposited by DC Magnetron Sputtering

Zinc Aluminum Oxide thin films were deposited on glass substrates by reactive DC magnetron sputtering method by varying oxygen flow rates from 1 to 4 sccm. Glancing angle X-ray diffraction patterns ofzinc aluminum oxide thin films exhibits (0 0 2) peak with c-plane preferentially oriented parallel to the substrate. The surface morphology and elemental analysis of the films was observed by field emission scanning electron microscopy attached with energy dispersive X-ray analysis spectroscopy. An average optical transmittance of 83–90% is obtained for the films deposited at various oxygen flow rates. The optical band gap of the films increases from 3.41 to 3.53 eV with the increase of oxygen flow rate due to Burstein–Moss effect. The optical dispersion parameters such as dispersion energy (Ed), oscillator energy (Eo) and static refractive index (no) were determined using the Wemple-DiDomenico (W-D) single oscillator model. The nonlinear optical parameters such as optical susceptibility (χ(1)), third order nonlinear optical susceptibility (χ(3)) and nonlinear refractive index (n2) were also determined.

Effect of oxygen flow rate on structural, electrical and optical properties of zinc aluminum oxide thin films deposited by DC magnetron sputtering -=SUP=-*-=/SUP=-

AbstractZinc Aluminum Oxide thin films were deposited on glass substrates by reactive DC magnetron sputtering method by varying oxygen flow rates from 1 to 4 sccm. Glancing angle X-ray diffraction patterns ofzinc aluminum oxide thin films exhibits (0 0 2) peak with c-plane preferentially oriented parallel to the substrate. The surface morphology and elemental analysis of the films was observed by field emission scanning electron microscopy attached with energy dispersive X-ray analysis spectroscopy. An average optical transmittance of 83–90% is obtained for the films deposited at various oxygen flow rates. The optical band gap of the films increases from 3.41 to 3.53 eV with the increase of oxygen flow rate due to Burstein–Moss effect. The optical dispersion parameters such as dispersion energy ( E _ d ), oscillator energy ( E _ o ) and static refractive index ( n _ o ) were determined using the Wemple-DiDomenico (W-D) single oscillator model. The nonlinear optical parameters such as optical susceptibility (χ^(1)), third order nonlinear optical susceptibility (χ^(3)) and nonlinear refractive index ( n _2) were also determined.

Al-doping and Properties of AZO Thin Films Grown at Room Temperature: Sputtering Pressure Effect

Aluminum zinc oxide (AZO) thin films were synthesized on glass substrates by radio frequency (rf) magnetron sputtering from a metallic Zn-Al (5 at. %) target at room temperature. The morphological, structural, electrical and optical properties of the films were studied as a function of the sputtering pressure, which was varied from 0.1 to 6.7 Pa. X-ray diffraction (XRD) analyses revealed that the films obtained were polycrystalline, having a hexagonal wurtzite structure with a preferential orientation in the (002) plane. In addition, the crystallite size increased as a function of sputtering pressure. Owing to the re-sputtering of the Zn atoms from the growing film, the aluminum concentration presented a maximum value of 13 at. %. At pressures close to 0.16 Pa, we obtained films with values of electrical resistivity and mobility of 2.8 10-3 Ω cm and 17 cm2/Vs, respectively. Finally, our results indicate that the structure zone diagram proposed by Thornton and later modified by Kluth does not fully predict the structural/morphological behavior of the AZO films, since plasma interactions must also be taken into account. With the methodology used, transparent conductive electrodes can be deposited on substrates at low temperatures.

Modulation of argon pressure as an option to control transmittance and resistivity of ZnO:Al films deposited by DC magnetron sputtering: on the dark yellow films at 10-7 Torr base pressures

In a previous paper, we reported that thin films of ZnO:Al [aluminum-zinc oxide (AZO)] deposited after achieving a very low base pressure [from 4.0×10–7 Torr (5.6×10–5 Pa) to 5.7×10–7 Torr (7.6×10–5 Pa)] result dark yellow in color and are resistive. These are undesirable characteristics for the application of AZO thin films as front electrodes in solar cells. However, given the increasingly tendency in the acquisition of equipment that allow us to reach excellent vacuum levels, it is necessary to find the deposition conditions that lead to an improving of transmittance without greatly impacting the electrical properties of materials deposited after achieving these levels of vacuum. In this way, the present work is focused on AZO thin films deposited after achieving a very low base pressure value: 4.2×10–7 Torr (5.6×10–5 Pa). For this, we studied the effect of the variation of the oxygen volume percent in the argon/oxygen mixture (by maintaining the deposition pressure constant) and the effect of deposition pressure with only argon gas on the main properties of AZO thin films. The depositions were done at room temperature on glass substrates by direct-current magnetron sputtering with a power of 120 W (corresponding to a power density of 2.63 W/cm2). As results, we found that the variation of deposition pressure with only argon gas is a good option for the control of optical and electrical properties, since the addition of oxygen, although improves transmittance, greatly impacts on the electrical properties. Furthermore, an interesting correlation was found between the optical and electrical properties and the chemical composition of the AZO films, the latter depending on the argon pressure (for this, a careful X-ray photoelectron spectroscopy analysis was performed). Also, the inverse relationship between crystallinity and deposition rate was confirmed, in which deposition rate inversely depends on argon pressure.

Degenerate optical nonlinear enhancement in epsilon-near-zero transparent conducting oxides

We report the simultaneous increase of both nonlinear Kerr coefficient n2 and third-order nonlinear susceptibility χ(3) in aluminum zinc oxide (AZO) attained by pump-probe spectroscopy in a frequency degenerate configuration. Our experiments demonstrate a 6-fold enhancement in the third-order nonlinear susceptibility and over one order of magnitude increase in the nonlinear Kerr coefficient, while also determining two distinct operational wavelengths for optimal modulation of either the real or the imaginary part of the complex refractive index. These results, besides providing a broader spectral characterization of the third-order nonlinearity in AZO thin films, also show the fundamental advantages of performing nonlinear optics via degenerate excitation near the ENZ wavelength.

Serial cosputtering for aluminum doping manipulated zinc oxide as front contact for Cu(In,Ga)Se2 solar cells

Aluminum zinc oxide (AZO) thin films were deposited by modified in-line direct current magnetron sputtering — so-called serial cosputtering — using two commercial rotatable targets. A metallic aluminum target (secondary target) was used to condition the surface of a rotatable ceramic aluminum-doped zinc oxide target (ZnO:Al2O3 wt %) as the primary target from which the film was deposited. Consequently, the direct current power applied to the secondary target enabled the variation of doping concentration in the deposited film. An optical transmittance >80% with an improved resistivity (<10−3 Ω·cm) and a higher carrier concentration (3 × 1020–6 × 1020 cm−3) were demonstrated in 300-nm-thick AZO thin films. AZO films with 2.23 at. % aluminum concentration used as the transparent conductive oxide (TCO) layer in copper indium gallium diselenide (CIGS) solar cells showed the best results with an efficiency of up to 13.2% due to an improved fill factor. The results reveal that adjusting the aluminum concentration could be used to match the electrical and optical characteristics of the TCO layer to those of the solar cells.

(Invited) Exploration of Process Techniques for Ga2O3 Based Electronics

Monoclinic β-phase Ga2O3 has outstanding potential for power electronics, and high quality, large diameter bulk crystals and epitaxial layers of Ga2O3 are already available with a range of controllable n-type doping levels by edge-defined film-fed (EFG) growth using iridium crucibles, by Czochralski or by float zone. The direct energy bandgap of Ga2O3, ∼4.9 eV, yields a very high theoretical breakdown electric field (∼8 MV/cm). For power electronics, the Baliga figure-of-merit proportional carrier mobility, critical electric field and breakdown voltage, is almost four times higher for Ga2O3 than for GaN. Currently, the major limitation for Ga2O3 based device fabrication is the lack of low resistance Ohmic contacts, low damage dry etching process, and thermally stable Schottky contacts. In this work, we report a technique by employing Aluminum Zinc Oxide (AZO) to improve Ohmic contacts on Ga2O3, studies of etch rates and etching induced damages with Cl2/Ar and BCl3/Ar based discharge as well as Ni/Au and Pt/Au Schottky contacts. High quality Ohmic contacts are a prerequisite for any device to deliver low contact resistance at moderate anneal temperatures. Additional contact resistance leads to slower device switching speeds as well as reliability issues due to local contact heating from high contact resistance during device operation. AZO thin films have been widely studied for transparent and flexible device applications such as liquid crystal displays, plasma display panels, electronic paper displays, organic light emitting diode, solar cells, touch panels, gas sensors and other optoelectronics devices. To be used as a contact layer on Ga2O3, a band alignment to ensure a less barrier to electron transport from the contact metal layer via AZO into the Ga2O3.is a prerequisite. The AZO/Ga2O3 heterojunction was realized with a nested gap alignment of band offsets with a valence band offset of 0.61eV ± 0.06eV and a conduction band offset of 0.79 eV ± 0.80 eV determined from x-RayPhotoelectron Spectroscopy (XPS) measurements. This is useful information for Ohmic contact schemes on n-type Ga2O3 devices. A minimum transfer resistance and specific contact resistance of 0.42 Ω-mm and 2.82 ´ 10-5 Ω-cm2 were achieved after a relative low annealing temperature of 400°C. It is essential to generate high resolution pattern transfer processes on semiconductor with wet chemical or dry etching. While numerous wet etchants been reported, these etching processes involve strong acids and elevated temperatures, and the standard positive photoresists will not be able to use as the etching mask. For dry etching, although, the etching rates are generally low, and the resultant oxygen deficient surfaces, standard device patterning and process are compatible with Ga2O3 based device fabrication. Both Cl2/Ar and BCl3/Ar discharges were used to etch high quality bulk Ga2O3 with a Plasma-Therm Inductively Coupled Plasma (ICP) system in this work. The etching is ion-enhanced and leads to a reduction of Schottky barrier height and diode reverse breakdown voltage in diodes fabricated on the etched surfaces depending on the rf and IPC powers. For low rf and ICP power conditions, the reverse breakdown voltage decreased around 6%, while barrier height reduced from 1.2 to 1.01 eV. Under higher power conditions, the reverse breakdown voltage decreased around 35%, and the barrier height was reduced to 0.86 eV. For Schottky diodes, Ni/Au or Pt/Au were used to form Schottky contact on bulk or epitaxial β- Ga2O3. The barrier heights were 1.07 and 1.04 eV for Ni/Au and Pt/Au, respectively, at 25°C. The diode on-state resistances (Ron) decreased with increasing temperature. The temperature coefficient of reverse breakdown voltage (VB), β, was −4 mV/K for Ni/Au and −0.1 mV/K for Pt/Au. The figure-of-merit (VB 2/RON) was above 3 MW/cm2 at 25°C for Ni/Au diodes and was still ∼1 MW/cm2 at 200°C. The reverse recovery times were also measured as a function of temperature and were of the order of 21–28 ns over the range 25–150°C.

Rare earth Eu3+ co-doped AZO thin films prepared by nebulizer spray pyrolysis technique for optoelectronics

Rare earth element (i.e.) europium co-doped aluminum zinc oxide (Eu:AZO) thin films were deposited on microscope glass slides by nebulizer spray pyrolysis with different Eu-doping concentrations (0, 0.5, 1, and 1.5%). The deposited films were investigated using X-ray diffraction, AFM, EDAX, FT-Raman, UV–visible, PL, and Hall effect measurements. X-ray confirmed the incorporation of aluminum and europium ions into the ZnO structure. All films have polycrystalline nature with hexagonal wurtzite structure at (002) direction. Topological depictions exhibited minimum surface roughness and low film thickness for pristine AZO thin film. EDAX study authorizes the existence of Zn, O, Al, and Eu in Eu: AZO thin films. Raman spectra exhibited the characteristic of ZnO-wurtzite structure (E2-high) mode at 447 cm−1. The deposited film showed high optical transmittance of ~90% in visible region, and the direct energy gap was around 3.30 eV for pristine AZO thin film. The PL spectra emitted a powerful UV emission situated at 388 nm, and it indicates that the film has good optical quality. The obtained large carrier concentration and less resistivity values are 4.42 × 1021 cm−3 and 3.95 × 10−4 Ω cm, respectively, for 1.5% Eu-doped AZO thin film. The calculated figure of merit value is 17.29 × 10−3 (Ω/sq)−1, which is more suitable for the optoelectronic device.

Broadband optical properties of aluminium zinc oxide thin films prepared by spatial atomic layer deposition

In this work, a broadband ellipsometric investigation of aluminium zinc oxide (AZO) from the infrared to the ultraviolet spectral range is presented. Aluminium zinc oxide samples were fabricated using spatial atomic layer deposition (SALD) having a range of percent aluminium incorporation. The AZO was deposited using a coflow of diethyl zinc (DEZ) and dimethyl aluminium isopropoxide (DMAI), where the amount of aluminium incorporation was controlled by varying the DMAI partial pressure. The broadband permittivity is reported as a function of the aluminium content of these aluminium zinc oxide thin films. A model dielectric function, which includes the contribution of recently predicted broad shallow donor states, is presented and discussed. We find that an increase in the aluminium content of the aluminium zinc oxide thin films results in a monotonically decreasing scattering time while the carrier density increases with diminishing efficiency. To demonstrate the necessity of broadband ellipsometric measurements for the accurate determination of the dielectric function of aluminium zinc oxide, a comparison with the classical Drude model and a semi-empirical extended Drude dispersion model, which are frequently employed in the literature to describe the optical response of aluminium zinc oxide, is given.

Effect of acetic acid and water content in the spray solution on structural, morphological, optical and electrical properties of Al and In co-doped zinc oxide thin films

Aluminium and indium co-doped zinc oxide (AIZO) thin films were deposited using ultrasonic spray pyrolysis. Depositions were performed by varying the acetic acid and water content in the spraying solution which resulted in the formation of different nanostructures like hexagons, flowers, chisels, curved nanostructures, hexagonal pyramids, super grown hexagons, and inter-connected nanostructures. Further, the physical properties such as structural, optical, electrical, and surface texture parameters were examined. The structural studies showed that films were of crystalline nature, with different crystallite sizes and grown with a preferential orientation along (002) plane. The optical transmittance assessments proved that films were highly transparent (> 80%) in the visible region. The electrical sheet resistance was found to be in the range 29–1K Ω/□. Surface parameters like average roughness, root mean square roughness, and peak-valley height values helped to understand the homogeneity of the thin films. Finally, the suitability of AIZO films for transparent conductive oxide applications were tested by estimating the figure of merit (FOM). Among the different solution conditions, films fabricated using a starting solution containing 25 ml of acetic acid and 25 ml of water exhibited the lowest resistivity (2.47 ± 0.03 × 10−3 Ω-cm) along with the highest FOM (5.83 ± 0.42 × 10−3/Ω).

Influence of spray-pyrolysis deposition parameters on the electrical properties of aluminium zinc oxides thin films

In the current work, we evaluate the influence of the processing parameters on the electrical properties of aluminium zinc oxide (AZO) thin films produced by airbrush spray-pyrolysis deposition technique. Spray-deposited AZO thin-films were produced with Al:Zn molar ratios varying from 0 % (pure ZnO) up to 30 %, using aluminium acetate and zinc acetate as organic precursors and water as solvent. Thermogravimetric analysis (TGA) and infrared spectroscopy (FTIR-ATR) were used to monitor the metal-oxide formation from the organic precursors as a function of the temperature. The results show that a temperature of 400 °C is necessary to completely degrade the organic phase and to obtain the desired inorganic metal-oxides films. The electrical properties of the TMOs were evaluated by d.c. current-voltage (I-V) analysis using planar thermally evaporated Al electrodes on top of the TMO layer, with different aspect ratios (1/18, 2/9, 5/13, 5/9 and 8/9). The lowest sheet resistance was obtained for AZO films at a molar Al concentration of 5 %. We also observed that, after carrying out a post-annealing treatment (30 mbar, 150 °C) the samples presented a decrease on the sheet resistance superior to 60 %, in comparison to the samples before the treatment.