Structural and electrical characterizations of ZnO:In/PS/Si heterojunction deposited by rf-magnetron sputtering
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Indium doped zinc oxide (IZO) thin film has been deposited on p-type porous silicon (PS) substrate by rf-magnetron sputtering of IZO aerogel nanoparticles at room temperature to obtain n-IZO/PS/p-Si heterojunction diode. The obtained IZO film, with a thickness of about 400 nm using indium concentration of 4 at.%, was polycrystalline with a hexagonal wurtzite structure and preferentially orientation in the (002) crystallographic direction. Atomic force microscopy (AFM) micrograph shows that IZO film has a typical columnar structure and a very smooth surface. The heterojunction parameters were evaluated from the current-voltage (I-V) characteristics carried out in the temperature range 80–300 K and capacitance-voltage (C-V) measurements. The ideality factor and barrier height of the heterojunction exhibited strong temperature dependence. The electrical measurements show that the n-IZO/PS/p-Si heterojunction has a Schottky electronic behavior where the depletion-layer is developed principally in the p-type silicon substrate. The tunneling mechanism via deep-level states was the main conduction process at low forward bias, while space-charge-limited current conduction dominated the carrier transport at higher bias. The I-V characteristics under illumination show that the p-n junction exhibits a photovoltaic behavior and is promising for photovoltaic application.