Method for forming a thin protection film

DETAILED DESCRIPTION It is an object of the present invention to provide a photosensitive a-SiC:H material which assures high light transmissivity, hardness and suitability for use as a photosensitive member and which is able to resist blurring under high humidity conditions without using a heating source.
Accordingly, the present invention provides a hydrogenated amorphous silicon carbide having a general formula a-Si.
sub.
1-x C.
sub.
x :H wherein the ratio of the TO peak amplitude appearing in the vicinity of 480 cm.
sup.
-1 observed by laser Raman spectroscopy measurement using an Ar.
sup.
+ 488 nm excitation laser to the TA peak amplitude appearing in the vicinity of 150 cm.
sup.
-1 is 2.
0 or more and the carbon content (x) is in the range of 0.
4 to 0.
8.
In accordance with the invention, investigations have been conducted to determine the surface behavior of an a-Si:H photosensitive member subjected to corona irradiation under high humidity conditions by measurement of the contact angle using high sensitivity reflection FT-IR (IR-RAS) techniques.
These investigations have shown that corona irradiation of the surface protecting layer of an a-Si:H photosensitive member under high humidity conditions causes an increase of Si-OH, HO-OH, Si-O-Si, NO.
sub.
3 - and CO.
sub.
3 -- at the surface, thereby enhancing wettability.
Ozone (O.
sub.
3) generated by corona irradiation directly oxidizes the surface of the photosensitive member and increases Si-O-Si coupling.
Simultaneously, absorption groups such as NO.
sub.
3 -, CO.
sub.
3 -- and OH are generated and such absorption groups adhere to Si at the surface as hydrates.
As a result, surface polarity and thus surface wettability are increased because the polar H.
sub.
2 O molecules tend to adhere to the surface.
When the surface is charged under such condition, charges flow and therefore blurring occurs.
In accordance with the present invention, wettability is improved (decreasing) by increasing the carbon content in a-Si.
sub.
1-x C.
sub.
x :H films of the type that are used currently as the surface protecting layer because, as explained above, it is not practical to employ materials that do not include Si at the surface to provide an a-Si photosensitive member which is resistive to humidity