Electrical and optical characteristics of aerosol assisted CVD grown ZnO based thin film diode and transistor

The prospect of developing thin film diodes (TFDs) and thin film transistors (TFTs) by using indigenously developed aerosol assisted chemical vapor deposition system is reported in this paper. Optical, structural, elemental and current (I) - voltage (V) characterization of fabricated structures manifest distinctly the properties of both TFT and TFT. UV-VIS spectroscopy shows that the average transmittance of single and multilayer thin films range between 80 and 95% implying that highly transparent deposition can be achieved. X-ray photoelectron spectroscopy manifest the deposition of ZnO, Al:ZnO and Al2O3 thin films. X-ray diffraction of the films confirm the polycrystalline type of deposition. I-V characteristics of In/n-ZnO/n+-Al:ZnO/In bi-layer structure suggests the fabrication of a TFD. Linear dependency of barrier height (BH) and exponential decrease of ideality factor of fabricated TFD with increasing temperature are observed. Modified Richardson plot is used to measure the inhomogeneity in BH and Richardson constant of In/n-ZnO/n+-Al:ZnO/In TFD. Transfer and output characteristics of the present TFT structure is found to be in agreement with those for a p-channel TFT system. The threshold voltage, saturation field effect mobility, subthreshold swing and current on/off ratio of the TFT were measured as 2.2 V, 24.3 cm2 V-1 s−1, 0.23 V/decade and 36, respectively.