The Performance Study Of Flexible Microwave Ge PIN Diode Under Bending Conditions

Flexible electronics have become a research focus for their distinctive properties such as light weight,robust and capability of being attached to uneven surfaces.Although flexible electronics have enabled some applications such as flexible display and electronic paper,they all work at low-speed range.More applications such as RFIDs,artificial skin,sensors call a high demand for microwave working capability of flexible electronics.Recently with the development of semiconductor nanomembrane transfer technique,researchers have been able to transfer semiconductor membranes from semiconductor-on-insulator onto plastic substrates and fabricated devices such as flexible TFTs and PIN diodes.And these devices have demonstrated good RF performance which indicates the possibility of flexible microwave systems.Previous researches have demonstrated the good performance of PIN diodes and TFTs adopting Si nanomembranes.In this study we give a thorough study about flexible PIN diode based on Ge nanomembrane.First we gave an introduction about the materials used in flexible electronics and about nanomembrane transfer technique.Then we introduced the layout and the fabrication process of flexible PIN diode.The performance of the fabricated PIN diode was tested under both transversal and longitudinal bending conditions and displays good performance under bending strains.The turn-on voltage of the diode remains unchanged at 0.35 V under bending strains.And the isolation is larger than about 10 dB at frequencies up to 20 GHz and shows negligible change under bending conditions,the insertion loss changes only 0.2dB from dc to 20 GHz.Finally an RF model was built to study the influence of bending strains on the PIN diode and the model shows good agreement with the experiment results and reveals the relation of the performance of the PIN diode and bending strains.