Si-based amorphous SnO2 vertical heterojunction photodetectors with high responsivity and nanosecond photoresponse

Photodetectors play a crucial role in the field of optoelectronic communications and other information-related domains. Si as one of the most important materials for visible light detection, has its performance constrained by factors such as its low absorption coefficient, which limits the further enhancement of commercial photodetector performance. In this work, by employing a SnO 2 heterojunction, we have fabricated a MSM structured photodetector with a vertical PN space charge region. The photoelectrons generated in the space charge region can be accelerated onto the SnO 2 surface and achieve sensitive spectral response. By varying the thickness of SnO 2 , the thickness of the space charge layer in the detector is gradiently modulated. Together with the photo-induced potential from KPFM characterization, the key role of the space charge layer thickness is fully confirmed in performance modulation of devices. The device achieves a maximum responsivity of 0.65 A/W and a quantum efficiency of 94.6 %. More notably, the transient response of the device is below 20 ns, demonstrating the application potential of this structure in photodetectors.