Low-temperature and catalyst-free synthesis of well-aligned ZnO nanorods on Si (100)

Well-aligned ZnO nanorods have been grown on Si (100) substrates using a simple, catalyst-free CVD method at low temperatures. Structural analyses show that the nanorods grown on Si (100) are preferentially oriented in the c-axis direction. An amorphous SiO_x layer in the interface of ZnO nanorods and Si (100) is observed from the HRTEM and EELS images. The well-aligned ZnO nanorods exhibit a strong PL emission of 380 nm at room temperature. A negligible green band emission in the PL spectra indicates that there is a very low concentration of oxygen vacancies in the highly oriented ZnO nanorods. Diameter control of the well-aligned and high-quality ZnO nanorods on Si (100) substrates is achievable by varying the growth conditions.