The finish of Moore's Law,the prediction that transistor density would double every two years, was one of the hottest topics in electronics-related discussions in 2015. Silicon-based technologies have nearly reached the physical limits of the number and size of transistors that can be crammed into one chip, or but alternative technologies are still far from mass implementation. The amount of heat generated during operation and the sizes of atoms and molecules in materials used in transistor manufacturing are some of problems that need to be solved for Moore's Law to persist.
Source: phys.org