A flexible InGaAs nanomembrane PhotoFET with tunable responsivities in near- and short-wave IR region for lightweight imaging applications

Abstract

An ultra-thin (15 nm) InGaAs nanomembrane field-effect phototransistor is transferred entirely from a rigid InP substrate onto a flexible SU-8 on a polydimethylsiloxane substrate. The transferred InGaAs device exhibits wide-band spectral response tunability up to 1.8 µm, from the visible to near-infrared light. Using an epitaxial lift-off process of InGaAs-on-InP MOSHEMT, the transferred device is inverted with a fully exposed channel for photosensitivity enhancement, while retaining three terminals for photocurrent amplification and modulation. The photocurrent can be tuned ∼5 orders over a gate bias range of 6 V. On-state photo-responsivities of 350 A/W to 15 A/W for 0.6 µm and 1.8 µm of light, respectively, is measured, ∼2 × higher than existing silicon and III-V photodetectors. Furthermore, the device shows no electrical performance degradation when flexed down to 10-cm radius, demonstrating suitability for conformal surface sensor applications.