Nano-Subsidence Assisted Precise Integration of Patterned Two-Dimensional Materials for High-Performance Photodetector Arrays.

The spatially precise integration of arrays of micro-patterned two-dimensional (2D) crystals onto three-dimensionally structured Si/SiO2 substrates represents an attractive, low-cost system-on-chip strategy towards realization of extended functions in silicon microelectronics. However, the reliable integration of such atomically thin arrays on planar patterned surfaces has proved challenging due to their poor adhesion to underlying substrates, as ruled by weak van der Waals interactions. Here we report on an integration method utilizing the flexibility of the atomically thin crystals and their physical subsidence in liquids, which enables reliable fabrication of the micro-patterned 2D materials/Si arrays. Our photodiode devices display peak sensitivity as high as 0.35 A/W and external quantum efficiency (EQE) of ~90%. The nano-subsidence technique represents a viable path to on-chip integration of 2D crystals onto silicon for advanced microelectronics.