Photo-excited charge collection spectroscopy: probing the traps in field-effect transistors

Solid state field-effect devices such as organic and inorganic-channel thin-film transistors (TFTs) have been expected to promote advances in display and sensor electronics. The operational stabilities of such TFTs are thus important, strongly depending on the nature and density of charge traps present at the channel/dielectric interface or in the thin-film channel itself. This book contains how to characterize these traps, starting from the device physics of field-effect transistor (FET). Unlike conventional analysis techniques which are away from well-resolving spectral results, newly-introduced photo-excited charge-collection spectroscopy (PECCS) utilizes the photo-induced threshold voltage response from any type of working transistor devices with organic-, inorganic-, and even nano-channels, directly probing on the traps. So, our technique PECCS has been discussed through more than ten refereed-journal papers in the fields of device electronics, applied physics, applied chemistry, nano-devices and materials science, finally finding a need to be summarized with several chapters in a short book. Device physics and instrumentations of PECCS are well addressed respectively, in the first and second chapters, for the next chapters addressing real applications to organic, oxide, and nanostructured FETs. This book would provide benefits since its contents are not only educational and basic principle-supportive but also applicable and in-house operational

Self-Aligned Top-Gate Amorphous Indium Zinc Oxide Thin-Film Transistors Exceeding Low-Temperature Poly-Si Transistor Performance

Thin-film transistor (TFT) is a key component of active-matrix flat-panel displays (AMFPDs). These days, the low-temperature poly silicon (LTPS) TFTs are to match with advanced AMFPDs such as the active matrix organic light-emitting diode (AMOLED) display, because of their high mobility for fast pixel switching. However, the manufacturing process of LTPS TFT is quite complicated, costly, and scale-limited. Amorphous oxide semiconductor (AOS) TFT technology is another candidate, which is as simple as that of conventioanl amorphous (a)-Si TFTs in fabrication but provides much superior device performances to those of a-Si TFTs. Hence, various AOSs have been compared with LTPS for active channel layer of the advanced TFTs, but have always been found to be relatively inferior to LTPS. In the present work, we clear the persistent inferiority, innovating the device performaces of a-IZO TFT by adopting a self-aligned coplanar top-gate structure and modifying the surface of a-IZO material. Herein, we demonstrate a high-performance simple-processed a-IZO TFT with mobility of ∼157 cm² V^–1 s^–1, SS of ∼190 mV dec^–1, and good bias/photostabilities, which overall surpass the performances of high-cost LTPS TFTs

Graphene Via Contact Architecture for Vertical Integration of vdW Heterostructure Devices

Two-dimensional (2D) devices and their van der Waals (vdW) heterostructures attract considerable attention owing to their potential for next-generation logic and memory applications. In addition, 2D devices are projected to have high integration capabilities, while maintaining nanoscale thickness. However, the fabrication of 2D devices and their circuits is challenging because of the high precision required to etch and pattern ultrathin 2D materials for integration. Here, the fabrication of a graphene via contact architecture to electrically connect graphene electrodes (or leads) embedded in vdW heterostructures is demonstrated. Graphene via contacts comprising of edge and fluorinated graphene (FG) electrodes are fabricated by successive fluorination and plasma etching processes. A one-step fabrication process that utilizes the graphene contacts is developed for a vertically integrated complementary inverter based on n- and p-type 2D field-effect transistors (FETs). This study provides a promising method to fabricate vertically integrated 2D devices, which are essential in 2D material-based devices and circuits.N

Visualization 1: Columnar deformation of human red blood cell by highly localized fiber optic Bessel beam stretcher

Irreversible stretching Originally published in Biomedical Optics Express on 01 November 2015 (boe-6-11-4417