Dear Samit Karmakar, several strategies have been implemented in recent years in order to open up the graphene's band gap for nanoelectronic applications. One of the well-known approaches is the synthesis of graphene nanomesh through etching of graphene basal plane using nanolithography techniques or chemical oxidation. Creation of such nanoholes on the graphene basal plane opens up the band gap and yields a holey nanosheet a suitable semiconductor for construction of transistors. To the best of my knowledge, most of the reported nanolithographic techniques are capable of controling the pits' sizes and in turn tailoring the graphene's band gap for a desired purpose. Furthermore, introduction of different heteroatoms such as nitrogen, oxygen and etc. to the chemical structure of graphene can engender a wider band gap as well. This intriguing topic is quite controversial and entails multitude of delicate details that cannot be brought up here. Below you can find a few papers which can help you to acquire a good insight on this area.

Article Graphene nanomesh: New versatile materials

Article Nanoporous graphene materials

Article Interfacial engineering in graphene bandgap

Best,

Dr. Behnam Farid