Chemical synthesis of pinecone like ZnO films for UV photodetector applications

Highly selective metal-semiconductor-metal (MSM) Ultra-Violet (UV) photodetectors were successfully demonstrated based on pinecone shaped zinc oxide (ZnO) films. The pinecone shaped ZnO photodetectors were synthesized via successive ionic layer by adsorption and reaction method (SILAR). The MSM device with silver (Ag) as contact electrode, possess simplicity in material synthesis and advantages in the device design and testing. Morphological evolution using SILAR method involves Ostwald's ripening process. The field emission scanning electron microscopy (FESEM) study reveals the formation of pinecone like ZnO structure with high surface area for adsorption of oxygen molecules. The device exhibited good photoresponse and spectral responsivity under ultraviolet (UV) illumination (power density 1.8 mu Wcm(-2)) at 5 V bias voltage. At 365 nm wavelength, the highest peak responsivity observed was 350.98 A/W. The device showed good ohmic contact between metal semiconductor junctions. Our finding provides new route for the fabrication of low cost and highly selective UV photoconductive detectors.