Interlayer Induced the Enhancement of Photoresponse Performance for ZnO Nanorods/CuS Heterojunction

Interface enhanced photodetectors based on n-ZnO nanorods/p-CuS heterojunctions are prepared by hydrothermal method with an insulated MgO insert layer. Through our investigation, with the help of the MgO film inserted between the interface of the ZnO NRs and CuS, the device shows a higher photodetectivity and a faster photoresponse speed. For the n-ZnO nanorods/p-CuS heterojunctions with MgO insert layer, the detectivity reached to ~ 2 × 10
¹³
cmHz
^1/2
/W at ~500 nm at -5 V, which is ~ 7 times bigger than that of the n-ZnO NRs/p-CuS heterojunction device (only 2.9 × 10
¹²
cmHz
^1/2
/W). Through energy band theory analysis, the improved performance is due to the improved interface, the enhancement of interfacial barrier and the decrease of carrier recombination when an insulated MgO layer is inserted between ZnO NRs and CuS.