In this research a bilateral tin oxide (SnO2) thin films was prepared by Sol-
Gel method, flow coating technique which is considered a simple and cheap
technique. The horizontal sample preparation with and without the use of
installed, and also with installed to vertical sample. Results of optical
spectroscopy that the biggest values of the transmittance T was for horizontal
films with an installed, as for the absorbance A was the biggest values of the
vertical sample. For the reflectivity R was value in the horizontal films with
installed, less than a horizontal films without Sticky as well as for films
vertical. The results of the energy gap Eg for that direct allowed and forbidden
transitions and for the indirect allowed and forbidden transfers for the studied
Samples were also calculated, and they showed that the highest value of Eg was
(3.85eV) for the direct forbidden transfers in the horizontal sample with
installer, while the lowest value of Eg was (3.65eV) for the indirect allowed
transfers without installer. The vertical film with indirect showed the lowest
value for the energy gap ever (3.45eV) for the indirect allowed transitions.