Crystallization and bleaching of diamond-like carbon and silicon oxynitride thin films
Optically transparent diamond-like carbon (DLC) thin films are formed using relatively low-temperature deposition conditions followed by a post-deposition bleaching step. The bleaching can include exposure of an as-deposited thin film to UV laser radiation, which reduces the concentration of defects in the film. The method is compatible with temperature-sensitive substrates, and can be used to form water clear DLC layers on glass substrates, for example, which can be used in display applications.
1. A method of forming an optically-transparent thin film, comprising,
providing a color-inducing defect-containing diamond-like carbon or silicon oxynitride thin film having an optical transparency on a substrate, wherein the color-inducing defect-containing thin film comprises graphitic defects; and
increasing the optical transparency of the color-inducing defect-containing diamond-like carbon or silicon oxynitride thin film to at least 90% by irradiating the color-inducing defect-containing thin film with ultraviolet radiation to reduce the concentration of the color-inducing defects within the color-inducing defect-containing thin film.
2. The method according to claim 1 , wherein providing a color-inducing defect-containing diamond-like carbon or silicon oxynitride thin film on a substrate comprises forming the color-inducing defect-containing thin film on the substrate via plasma enhanced chemical vapor deposition.
3. The method according to claim 1 , wherein providing a color-inducing defect-containing diamond-like carbon or silicon oxynitride thin film on a substrate comprises forming the color-inducing defect-containing thin film on the substrate via RF-PECVD.
4. The method according to claim 1 , wherein providing a color-inducing defect-containing diamond-like carbon or silicon oxynitride thin film on a substrate comprises forming the color-inducing defect-containing thin film on the substrate at a deposition temperature of less than about 400° C.
5. The method according to claim 1 , wherein providing a color-inducing defect-containing diamond-like carbon or silicon oxynitride thin film on a substrate comprises forming the color-inducing defect-containing thin film on the substrate at a deposition temperature of less than about 100° C.
6. The method according to claim 1 , wherein the substrate comprises a material selected from the group consisting of glass, plastic, wood and metal.
7. The method according to claim 1 , wherein the substrate is a glass substrate.
8. The method according to claim 1 , wherein a source of the ultraviolet radiation is a KrF pulsed laser.
9. The method according to claim 1 , wherein the ultraviolet radiation has a wavelength of about 248 nm.
10. The method according to claim 1 , wherein the ultraviolet radiation comprises laser radiation and irradiating the color-inducing defect-containing thin film with ultraviolet radiation further comprises scanning the ultraviolet radiation over a surface of the color-inducing defect-containing thin film.
11. The method according to claim 1 , wherein the color-inducing defect-containing thin film is irradiated for less than 5 min.
12. The method according to claim 1 , wherein an irradiated region of the optically-transparent thin film is substantially free of graphite.
13. The method according to claim 1 , wherein the optically-transparent thin film has a thickness of from about 100 nm to about 5000 nm.