Fig. 1: Programmable bP phototransistor (bP-PPT) array.
From: Programmable black phosphorus image sensor for broadband optoelectronic edge computing
a The bP-PPT array is capable of multispectral infrared imaging and is programmable for in-sensor computing. The array can be programmed remotely using optical control signals and locally using electrical gate voltages. b The layer structure of a bP-PPT device. c Optical microscope image of a 3 × 4 array of bP-PPT devices patterned on a single bP flake. The white dashed square indicates a patterned bP device. Scale bar: 10 μm. d Band diagram of the bP-PPT device. The AHA dielectric stack is designed to store charges in the HfO2 layer. The electron affinity (\(\chi\)), bandgap (\({E}_{g}\)), and work function (W) of the layers are: \({\chi }_{{{{{{\rm{A}}}}}}{{{{{{\rm{l}}}}}}}_{2}{{{{{{\rm{O}}}}}}}_{3}}=1.0\,{{{{{\rm{eV}}}}}}\), \({E}_{g,{{{{{\rm{A}}}}}}{{{{{{\rm{l}}}}}}}_{2}{{{{{{\rm{O}}}}}}}_{3}}=7.7\,{{{{{\rm{eV}}}}}}\), \({\chi }_{{{{{{\rm{Hf}}}}}}{{{{{{\rm{O}}}}}}}_{2}}=2.5\,{{{{{\rm{eV}}}}}}\), \({E}_{g,{{{{{\rm{Hf}}}}}}{{{{{{\rm{O}}}}}}}_{2}}=4.9\,{{{{{\rm{eV}}}}}}\), \({E}_{{{{{{\rm{trap}}}}}}}\) = 1.25 eV, \({\chi }_{{{{{{\rm{bP}}}}}}}\) = 4.4 eV, \({E}_{g,{{{{{\rm{bP}}}}}}}\) = 0.3 eV, \({W}_{{{{{{\rm{Ni}}}}}}}=5.01\,{{{{{\rm{eV}}}}}}\), \({W}_{{{{{{\rm{ITO}}}}}}}\) = 4.7 eV. e. Ids–VG measurement of nine bP-PPT devices. Each bP-PPT shows a large memory window of 25 V in VG and an on-off ratio of ~200. The inter-device variation (standard deviation) in the array is shown as the gray shaded area. Inset: histogram of the on-off ratio of the devices in the array.
