Laser Machining of Graphene

Since Geim and Novoselov’s successful production of high quality graphene, its unique properties have found a number of applications. But graphene is not an exotic chemical compound; instead, it is a sheet of graphite, one atom think. Before 2008, the only way to produce graphene was through successive pealing of graphite with scotch tape until graphite flakes as thin as 1 atomic layer were left [14]. This method, known as mechanical exfoliation, can only produce very small flakes of graphene, the longest being only100μm in length [7]. However in 2008 a new method of growing graphene known as chemical vapor deposition (CVD) was discovered [16]. This can produce graphene sheets as large as 30 inches [1]. With these extremely large sheets, the need to economically cut graphene without altering it’s properties grew. Current methods use techniques implemented in microelectronics fabrication. Oxygen-plasma etching is the most common method used to pattern graphene, but this method uses harsh chemicals, which can negatively alter graphene’s properties. As an alternative, electron microscopes can be used to remove unwanted graphene. In this method, the electron beam can be intensified high enough to remove carbon atoms form graphene lattice with atomic resolution, but this process can also negatively affect graphene. Laser cutting of graphene offers a quick and cost effective method of direct patterning graphene, without negatively affecting graphene’s properties. We have conducted a study using a continuous wave laser to machine graphene into the desired shapes. The success of the cut in graphene was determined when an electrical current could not be passed from one side of the cut to the other (determining if electrical contact between two regions was severed by the laser).