PREPARATION AND CHARACTERIZATION OF POROUS ZnONANOSTRUCTURES GROWN ONTO SILICON SUBSTRATE

摘要

Zinc oxide (ZnO) thin film (approximately 1.1 μm) was synthesized onto a Si(100)substrate by radio frequency (rf) sputtering with 200 W rf power for 120 min. The porousnanostructure of the film was prepared through electrochemical etching with electrolytesolution containing ethanol and nitric acid at a current density of 50 mA/cm2 and constantetching time of 120 s. Scanning electron microscopy images showed that the ZnOnanoparticles featured plate-like shape and covered the entire Si(100) substrate. After theporous process, the surface of the ZnO film became smooth, the plates or large particlesdisappeared, and nanosized pores were uniformly distributed. X-ray diffraction patternsconfirmed that the ZnO/Si(100) thin film exhibited higher crystallinity, with hexagonalphase growing toward the c axis, than that of the porous ZnO/Si(100) nanostructure. Thephotoluminescence (PL) spectrum showed that the intensity of the near-band edge of theZnO/Si peak was higher than that of the P–ZnO/Si peak. Furthermore, the number ofdefects in P–ZnO/Si(100) increased when the ratio of PL intensity for IUV to Idefectdecreased from 36.17 for ZnO/Si sample to 1.44 for porous ZnO/Si.