Tailoring the energy band in flexible photodetector based on transferred ITO/Si heterojunction via interface engineering

Interface engineering is an important method to modulate electronic structures for improving the physical properties of semiconductors as well as designing novel devices. Recently, development of flexible electronic devices based on inorganic thin films on flexible substrates, which provides solutions to meet the emerging technological demands, may also expend the methodology of interface engineering. Herein, a semitransparent photodetector based on an indium-tin oxide (ITO)-on-silicon (Si) heterojunction was fabricated on a flexible substrate and investigated under mechanical bending strains. It is found that the barrier height of the heterojunction can be tailored continuously and reversibly from 0.23 eV to 0 eV, corresponding to the Schottky and Ohmic junctions respectively. Meanwhile, the turn-on voltage and the response time of the as-prepared photodetector can be obviously reduced under bending strain, which can be attributed to the modulation of the Si bandgap and hole mobility. Our experimental studies not only shed new light on the strain modulation mechanism of the heterojunction interface, but also pave a prominent way to integrated high-performance flexible photodetectors.