Self-biased wavelength selective photodetection in an n-IGZO/p-GeSe heterostructure by polarity flipping

Transparent semiconductor oxides with two-dimensional (2D) heterostructures have been extensively studied as new materials for thin-film transistors and photosensors due to their remarkable photovoltaic characteristics, making them useful for newly developed optoelectronics. Here we demonstrate the fabrication and characterization of an ITO/n-IGZO/p-GeSe transparent selective wavelength photodetector. The wavelength-dependent photovoltaic behavior of the n-IGZO/p-GeSe heterostructure under UV-Visible laser light shifts the I-V curves down with positive V-oc and negative I-sc values of about 0.12 V and -49 nA and 0.09 V and -17 nA, respectively. Interestingly, when an NIR laser irradiated the device, the I-V curves shifted up with negative V-oc and positive I-sc values of about -0.11 V and 45 nA, respectively. This behavior is attributed to the free carrier concentration induced by photogenerated carriers across the device at different points that varied with the wavelength-dependent photon absorption. Consequently, the direction of the electric field polarity across the junction can be flipped. This study demonstrates a zero-bias near-infrared (NIR) photodetector with a high photoresponsivity of 538.9 mA W-1, a fast rise time of 25.2 ms, and a decay time of 25.08 ms. Furthermore, we observed a detectivity (D) of 8.4 x 10(9) Jones, a normalized photocurrent to dark current ratio (NPDR) of 2.8 x 10(10) W-1, and a noise equivalent power (NEP) of 2.2 x 10(-14) W Hz(-1/2). Our strategy opens alternative possibilities for scalable, low-cost, multifunctional transparent near-infrared photosensors with selective wavelength photodetection.

Automated summary

Transparent semiconductor oxides with two-dimensional heterostructures have been extensively studied for their remarkable photovoltaic characteristics, and this study demonstrates a transparent near-infrared photodetector with high photoresponsivity and fast response time. The device shows wavelength-dependent photovoltaic behavior and the direction of the electric field polarity across the junction can be flipped.