STUDY OF PHOTOCONDUCTIVITY IN THIN AMORPHOUS DIAMOND-LIKE CARBON (A-DLC) FILMS PREPARED BY RF GLOW-DISCHARGE TECHNIQUE

Thin a:DLC films were deposited by r.f. plasma system in which methane (CH4) was admitted. Photoconductivity measurements were performed on an Al-a:DLC-Cu sandwich structure and an Al-a:DLC-Al planar structure. The photocurrent was measured in a wide interval of temperatures. The photocurrent signal of the sandwich device is about 100 times higher than the dark current measured under He-Ne laser incident light (2.5 m W) at 160 K. A photocurrent response time of tau(o) approximate to 8 m s was measured at this temperature. In the planar device, under the sa me conditions, the photocurrent signal was twice the dark current. The maximum mobility-lifetime product of a:DLC (sandwich device) was abou t 2 x 10(-10) cm(2)/V.