I-V characteristics of n-ZnO∕poly-Si thin film heterostructure

Abstract

ZnO has been extensively studied for many different applications, such as gas sensors, transparent conductive electrodes in solar cells and light emitting diodes, etc., because of its chemical stability and sensitivity to different adsorbed gases, amenability to doping, large energy gap, nontoxicity and low cost. ZnO thin films have been applied for device engineering in different heterostructures, as well. In this work the I‐V characteristics of two thin film heterostructures n‐ZnO/p‐poly‐Si with ZnO films with different thicknesses, 80 and 300 nm are studied. The ZnO polycrystalline films are deposited by RF sputtering in an atmosphere of Ar on the surface of a p‐type poly‐Si layer. The poly‐Si films are prepared on glass substrate by the method of Aluminum Induced Crystallization (AIC) from precursor layers of Al and a‐Si:H. The Al and a‐Si:H precursor films are deposited by magnetron sputtering on glass substrate. The a‐Si:H film precursors contain 9 at.% hydrogen. The isotermal annealing of the structure glass/Al/a‐Si:H is performed in forming gas (N2+5%H2) in the temperature range of 530° C–550° C for 7 and 21 h. The properties of the films are studied by X‐Ray Diffraction (XRD), optical microscopy, optical transmission and reflection, and Raman spectrioscopy. The I‐V characteristics of the thin films heterostructures n‐ZnO/poly‐Si show diode behaviour and ideality factor of 2.2 and 3.5. The structures exhibit photosensitivity under illumination.