High-Performance Broadband Photo-Detection in Solution-Processed ZnO-ZnCr2O4Nanowalls

Abstract

We demonstrate high performance broadband UV-to-NIR detection, which is a critical issue associated with ZnO-based photodetectors. The as-synthesized ZnO-ZnCr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> nanowalls were first time utilized for broadband, i.e., 250-850 nm photo-detection (both in front and back illumination configurations). The dark current was found to be as low as 0.12 nA. The device has shown peak sensitivity for the UV region (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex</sub> = 350 nm) with the photo-sensitivity of ~1.28×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> , photo-responsivity of 5.49 AW-1, photo-detectivity of 1.91 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> cmHz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , linear dynamic range of 82 dB, and external quantum efficiency of 1900%. In addition, the white light emission (CIE coordinates of 0.32 and 0.34) was also observed in the ZnO-ZnCr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> nanowalls. This letter will open new directions in oxide semiconductors-based optoelectronic devices.