Hydrogen removal from hydrogenated diamond-like carbon films by exposure to photon and energetic atomic oxygen beams

Abstract

Stability of hydrogen in diamond-like carbon (DLC) film under simulated space environment, i.e., hyperthermal atomic oxygen, vacuum ultraviolet (VUV) and soft X-ray exposures has been studied. Hydrogen in DLC was released by exposure to low-energy atomic oxygen beam, whereas the gasification reaction of carbon atom needed collision energy above 3 eV. The desorption process in the deep region required a higher collision energy. The density of hydrogen decreased 11% by atomic oxygen exposure, and was independent of the collision energy. Photon exposure also releases hydrogen from DLC. High-energy photons in soft x-ray promote the hydrogen desorption even from deeper region with high efficiency. It was considered that soft x-ray could release bonded hydrogen which is not released by VUV or atomic oxygen exposures.