Temperature Dependence of Planar-type Graphite Structures

We have characterized the temperature dependence of the transport behavior for planar-type structures along ab-plane fabricated in micron-scale graphite layers. The planar-type structures of graphite layers were fabricated by using a focused ion])earn (FIB) etching method. In-plane areas of 10 mu m x 10 mu m, 6 mu m x 5 mu m, 6 mu m x 2 mu m, and 1 mu m x 1 mu m exhibit semi-conducting behaviors which is contradictory to conventional metallic behavior of graphite flakes and show a small drop in resistance around 49 K. The origin of this effect is suspected from Ga(+) ion damage during FIB fabrication. The fabricated planar-type structures show a transition in the current (1) - voltage (V) curves from diode-like characteristics around 30 K to an Ohmic behavior around 300 K.