We reported the analysis and modeling of some conduction mechanisms in ultrathin aluminum oxide (Al₂O₃) films of 6 nm thickness, which are deposited by atomic layer deposition (ALD). This modeling included current-voltage measurements to metal-insulator-semiconductor (MIS) capacitors with gate electrode areas of 3.6 × 10⁻⁵ cm² and 6.4 × 10⁻⁵ cm² at room temperature. The modeling results showed the presence of ohmic conduction, Poole Frenkel emission, Schottky emission, and trap-assisted tunneling mechanisms through the Al₂O₃ layer. Based on extracted results, we measured a dielectric conductivity of 5 × 10⁻¹⁵ S/cm at low electric fields, a barrier height at oxide/semiconductor interface of 2 eV, and an energy trap level into bandgap with respect to the conduction band of 3.11 eV. These results could be affected by defect density related to oxygen vacancies, dangling bonds, fixed charges, or interface traps, which generate conduction mechanisms through and over the dielectric energy barrier. In addition, a current density model is developed by considering the sum of dominant conduction mechanisms and results based on the finite element method for electronic devices, achieving a good match with experimental data.

In the present work, a study of the structural defects in HfO₂ thin films deposited by dip-coating on p-type silicon substrates treated under different conditions, such as air-annealing, ultraviolet irradiation, and simultaneous annealing–UV irradiation, is presented. HfO₂ thin films were analyzed by grazing incidence X-ray diffraction, Raman spectroscopy, optical fluorescence, atomic force microscopy, and UV-Vis diffuse reflectance. Films treated at 200 °C and 350 °C present peaks corresponding to monoclinic HfO₂. After UV treatment, the films became amorphous. The combination of annealing at 350 °C with UV treatment does not lead to crystalline peaks, suggesting that UV treatment causes extensive structural damage. Fluorescence spectroscopy and UV-Vis spectroscopy suggest that films present oxygen vacancies as their main structural defects. A reduction in oxygen vacancies after the second thermal treatment was observed, but in contrast, after UV irradiation, fluorescence spectroscopy indicated that more defects are created within the mobility gap, irrespective of the simultaneous annealing at 350 °C. An electronic band diagram was proposed assigning the observed fluorescence bands and optical transitions, which, in turn, explain the electrical properties of the films. The results suggest that the electronic structure of HfO₂ films can be tailored with a careful choice of thermal annealing conditions along with the controlled creation of defects using UV irradiation, which could open the way to multiple applications of the materials either in microelectronics, optoelectronics, as well as in photocatalytic/electrocatalytic applications such as photodegradation and hydrogen generation.

Thin film transistors (TFTs) fabricated on flexible and large area substrates have been studied with great interest due to their future applications. Recent studies have developed new semiconductors such as a-SiGe:H for fabrication of high performance TFTs. These films have important advantages, including deposition at low temperatures and low pressures, and higher carrier mobilities. Due to these advantages, the a-SiGe:H films can be used in the fabrication of TFTs. In this work, we present an analytical drain current model for a-SiGe:H TFTs considering density of states and free charges, which describes the current behavior at sub-and above- threshold region. In addition, 2D numerical simulations of a-SiGe:H TFTs are developed. The results of the analytical drain current model agree well with those of the 2D numerical simulations. For all characteristics of the drain current curves, the average absolute error of the analytical model is close to 5.3%. This analytical drain current model can be useful to estimate the performance of a-SiGe:H TFTs for applications in large area electronics.

In the present work, a study of the structural defects in HfO2 thin films deposited by dip-coating on p-type silicon substrates treated under different conditions, such as air-annealing, ultraviolet irradiation, and simultaneous annealing-UV irradiation, is presented. HfO2 thin films were analyzed by grazing incidence X-ray diffraction, Raman spectroscopy, optical fluorescence, atomic force microscopy, and UV-Vis diffuse reflectance. Films treated at 200 ºC and 350 ºC present peaks corresponding to monoclinic HfO2. After UV treatment, films became amorphous. The combination of annealing at 350 ºC with UV treatment does not lead to crystalline peaks, suggesting that the UV treatment causes extensive structural damage. Fluorescence spectroscopy and UV-Vis spectroscopy suggested that films present oxygen vacancies as the main structural defects. A reduction of oxygen vacancies after a second thermal treatment was observed, but in counterpart, after UV irradiation, fluorescence spectroscopy indicates that more defects are created within the mobility gap, irrespectively of the simultaneous annealing at 350 ºC. An electronic band diagram was proposed assigning the observed fluorescence bands and optical transitions. The results suggest that the electronic structure of HfO2 films can be tailored with a careful choice of thermal annealing conditions along with the controlled creation of defects using UV irradiation, which would open the way to multiple applications of the materials either in microelectronics and photocatalytic/electrocatalytic applications such as photodegradation and hydrogen generation.