Toward All-Carbon Electronics: Fabrication of Graphene-Based Flexible Electronic Circuits and Memory Cards Using Maskless Laser Direct Writing

Jiajie Liang, Yongsheng Chen 

Graphene is emerging as a novel 2D material in the field of materials science because of its intrinsic electronic, thermal, mechanical, structural and chemical properties. How ever, to fully realize its potential for all the proposed devices, once key is to develop an easy method to fabricate patterned graphene films.

Lately, the advanced technique of laser direct cutting, which has the advantages of maskless, rapid prototyping, reliability, amenability, upward scalability, and low cost, is of increasing importance in device fabrication and has been used to construct microstructures on various films of semiconductor, metal, and dielectric polymer

However, it is still a big step away using this technique to meet the need for fabricating the real-world micro/nano- electronic circuits and devices. To date, two key issues remain for this technique. First, the silicon-based semiconducting microstructures fabricated with the laser-writing technique make it rather difficult to have a clean structure and thus are unusable because of the nonvolatile remains. Second, as to the fabrication of organic or polymer films using this technique, their relatively poor chemical stability and resistance likewise extremely handicap their further use in this field. In this paper, the researchers describe a maskless process to fabricate all-carbon electronic circuits using a continuous graphene film prepared from a graphene solution spin-coating process followed by maskless laser writing.

Of great significance is that this writing process could be operated directly in air at ambient conditions, and various patterns used for electrical circuits and devices can be easily achieved.

On this basis, a novel prototype of write-once-read-many-times (WORM) memory cards along with a data-retrieving system has been demonstrated, the WORM were made on different substrates: flexible polyimide, quartz, and glass substrates. Then and graphene oxide solutions were spin coated to get uniform thin layers. Finally they were reduced to have graphene, over them small thin-film gold squares were deposited to act as the electrodes.

Remarkably, owing to the extraordinary chemical stability of graphene, these graphene-based WORM memory cards possess almost infinite data retention time and extreme reliability, which are crucial in the practical use of some memory devices, such as identification cards, radio- frequency tags, passports, e-tickets, and military applications.