Flexible Transient Phototransistors by Use of Wafer-Compatible Transferred Silicon Nanomembranes.

Flexible transient photodetectors, a form of optoelectronic sensors that can be physically self-destroyed in a controllable manner, could be one of the important components for future transient electronic systems. In this work, a scalable, device-first, and bottom-up thinning process enables the fabrication of a flexible transient phototransistor on a wafer-compatible transferred silicon nanomembrane. A gate modulation significantly restrains the dark current to 10-12 A. With full exposure of the light-sensitive channel, such a device yields an ultrahigh photo-to-dark current ratio of 107 with a responsivity of 1.34 A W-1 (λ = 405 nm). The use of a high-temperature degradable polymer transient interlayer realizes on-demand self-destruction of the fabricated phototransistors, which offers a solution to the technical security issue of advanced flexible electronics. Such demonstration paves a new way for designing transient optoelectronic devices with a wafer-compatible process.