Interfacial passivation by using an amorphous hafnium oxide thin layer toward improved CH3NH3PbI3/Si heterojunction photodetectors

In this paper, we reported the fabrication of improved CH3NH3PbI3/Si heterojunction photodetectors (PDs) achieved by passivating the interfacial defects by a low-temperature atomic layer deposition-grown thin amorphous HfO2 layer. The results suggested that the HfO2 thin layer effectively passivated the surface defects of Si and slightly improved the qualities of CH3NH3PbI3 thin films in terms of increasing the grain sizes. Current–voltage measurements suggested that the HfO2 thin layer suppressed interfacial Shockley–Read–Hall recombination, which decreased the dark current and simultaneously increased the photocurrent. However, a thick HfO2 layer resulted in a decrease in the photocurrent because of the insulting nature of HfO2. A champion performance was obtained by employing a 5 nm HfO2 layer, where the responsivity and detectivity were 0.6 mA/W and 8.0 × 1010 Jones, respectively, which are two times and four times as high as those PDs without the HfO2 layer. The results will provide a simple strategy for improving the performance of perovskite/Si heterojunction PDs in the future.