Low frequency noise and photo-enhanced field emission from ultrathin PbBi2Se4 nanosheets

Atomically thin two-dimensional layered materials have gained wide interest owing to their novel properties and potential for applications in nanoelectronic and optoelectronic devices. Here, we present the spectral analysis and photo-enhanced field emission studies of a layered intergrowth PbBi2Se4 nanosheet emitter, performed at the base pressure of ∼1 × 10−8 mbar. The emitter shows a turn-on field value of ∼4.80 V μm−1, corresponding to an emission current density of ∼1 μA cm−2. Interestingly, when the cathode was illuminated with visible light, it exhibited a lower turn-on field of ∼3.90 V μm−1, and a maximum emission current density of ∼893 μA cm−2 has been drawn at an applied electric field of ∼8.40 V μm−1. Furthermore, the photo-enhanced emission current showed reproducible, step-like switching behavior in synchronous with ON–OFF switching of the illumination source. The emission current–time plots reveal excellent stability over a duration of ∼6 h. Low-frequency noise is a significant limitation for the performance of nanoscale electronic devices. The spectral analysis performed on a Fast Fourier Transform (FFT) analyzer revealed that the observed noise is of 1/fα type, with the value of α ∼0.99. The low frequency noise, photo-enhanced field emission, and reproducible switching behavior characterized with very fast rise and fall times propose the layered PbBi2Se4 nanosheet emitter as a new promising candidate for novel vacuum nano-optoelectronic devices.