Molecular layer modulation of two-dimensional organic ferroelectric transistors.

Ferroelectric transistors hold great potential in low consumption devices. Due to the high film quality and clean system, two dimensional organic semiconductors are widely employed to fabricate high performance organic electronic devices and explore the modulation mechanism of the molecular packing on device performance. Here, we combine the ferroelectric hafnium oxide HfZrOxand two-dimensional molecular crystal 2,9-didecyldinaphtho[2,3-b:2',3'-f]thieno[3,2b]thiophene (C10-DNTT) with controllable layers to study the molecular layer modulation of ferroelectric organic thin-film transistors (OTFTs). The contact resistance, driving current and transconductance are directly affected by the additional access resistance across the upper molecular layers at the source/drain contact region. Simultaneously, the capacitance of Schottky junction related to the molecular layer thickness could effectively adjust the gate potential acting on the organic channel, further controlling the devices' subthreshold swing and transconductance efficiency. This work would promote the development of low voltage and high performance OTFTs.

Hermetic Welding of an Optical Fiber Fabry-Pérot Cavity for a Diaphragm-Based Pressure Sensor Using CO2 Laser.

A diaphragm-based hermetic optical fiber Fabry-Pérot (FP) cavity is proposed and demonstrated for pressure sensing. The FP cavity is hermetically sealed using one-step CO2 laser welding with a cavity length from 30 to 100 µm. A thin diaphragm is formed by polishing the hermetic FP cavity for pressure sensing. The fabricated FP cavity has a fringe contrast larger than 15 dB. The experimental results show that the fabricated device has a linear response to the change in pressure, with a sensitivity of -2.02 nm/MPa in the range of 0 to 4 MPa. The results demonstrate that the proposed fabrication technique can be used for fabricating optical fiber microcavities for sensing applications.