In the present work we have synthesized low density aligned carbon nanotubes using ethanol as a precursor and ferrocene as a catalyst by simple thermal chemical vapor deposition (CVD) method on silicon substrates. The synthesis involves the pyrolysis of ethanol/ ferrocene solutions. Mist of the hydrocarbon/catalyst is produced by medical nebulizer and nitrogen gas is used as the carrier to the large size (75 mm diameter and 1 metre long) tube which is designed to produce nanotubes in large quantity once growth process is optimized for particular application. The growth temperature of the chamber is varied in wide range. In the synthesis process, temperature is found to be crucial for the formation of carbon nanotubes. Different types (in terms of size and shape) of nanotubes are grown. at 800degC Short and closely uniform sized nanotubes are formed at 850degC. Furthermore, very interestingly we obtained low density vertical aligned nanotubes which has potential application in various electronic devices such as, field emitter and conducting electrodes, etc. Our effort to reproduce the straight uniformed nanotube along with the low density vertically aligned nanotubes was successful in spray pyrolysis method. Long nanotubes of different length and diameters are observed at 900degC. The tubes are observed to be temperature dependent. TEM investigations of these nanotubes also will be reported.