Ion-Beam Deposition of Thin Films of Diamondlike Carbon

Abstract

An ion-beam deposition technique has been developed and was used to deposit thin films of insulating carbon on room-temperature substrates. It was established that the carbon films deposited using this technique are insulating and have the following characteristics similar to that of carbon in the diamond form: (1) transparency, (2) index of refraction greater than 2.0, (3) highly insulating, (4) able to scratch glass, (5) resistant to hydrofluoric acid for long periods of time, (6) at least partially crystalline and with a lattice constant similar to diamond as demonstrated by x-ray diffraction, (7) dielectric constant between about 8 and 14 (diamond is 16.5). A resistance to sodium ion diffusion has been experimentally demonstrated. Preliminary measurements at a dose of 1 Mrad indicated a radiation resistance from the point of view of stability of leakage resistance and of negligibly small flat band voltage shifts. Several coplanar thin-film transistors using the insulating carbon gate have been fabricated.