In this work the semiconductor properties of a-Fe₂O₃ (hematite) with differents carriers density, N_D, were studied. This oxide was obtained from iron oxyhydroxide thin films (FeOOH) prepared using the H₂O₂ reduction reaction on a conductor glass FTO (SnO₂:F). This reaction takes place in the interface: FTO / 0.1 M H₂O₂ + 0.05 M FeCl₃ + 0.05 M NaF at 50ºC. To obtain a-Fe₂O₃ with differents N_D, the oxy–hydroxide precursor was synthesized by the repetitive potential pulses technique. This E/t program consisted to apply a cathodic potential E_C = -0.9 V during a time 0.5 s ≤ t_C ≤ 5 s and after, an anodic potential 0.0 V ≤ E_A ≤ 0.5 V was aplied during a time t_A = 5 s. At E_C, onto surface the OH^- electrogeneration and iron oxy–hydroxide precipitation take place. At E_A, it is procured that Fe(III) deposited maintains its oxidation state. The electrodeposition process was stopped when the total time at E_C was 30 min. Then, FeOOH thin film was transformed into a-Fe₂O₃ upon heat treatment at 525ºC by 30 min. This phase was characterized morphological and estructurally by SEM and XRD, respectivelly. By Orange II method, a roughness factor 17 ± 2 was determinated. This is in agree with dendritic structure observed by SEM. From Mott-Schottky plot obtained at 10 kHz in 0.1 M NaOH, the flat band potential (E_FB = -0.63 V vs HNE) and the donors density, N_D, were determined. N_D was dependent of anodic potential, E_A, that was used during the oxyhydroxide precursor formation. In general, N_D decreased from 1.2 10¹⁹ cm^-3 at E_A = 0.0 V until 2,2 10¹⁷ cm^-3 at E_A = 0.5 V. Photocurrent transients (PCT) and cyclic photovoltammetry in an 0.05 M NaI + 0.1 M NaOH solution were measured. These results are discussed considering the processes associated to the electron-hole pair generation, charge transfer in the interface, hole diffusion and electron-hole pair recombination.

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