Review on emerging research topics with key-route main path analysis

The fast development of the emerging research topics field results in hundreds of theoretical and empirical publications. However, to our knowledge, there is no comprehensive and objective literature review on this field until now. To this end, a citation network consisting of 1607 papers between 1965 and early 2019 is explored to discover the knowledge diffusion trajectory of the emerging research topics field by the key-route main path analysis approach, armed with the traversal weight of search path link count. From the convergence-divergence patterns in the local and global main paths, the development of emerging research topics field can be divided into three different stages: the emergence, exploration and development stages. In the meanwhile, several research drifts can also be observed: (1) from citation-based approaches to machine learning based ones, (2) from the measurement to the identification, and (3) from the papers to the patents. Finally, the directions of future research are suggested.