A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for the precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows one to reach a satisfactory precision at lower sample pressures, which reduces the influence due to collisions. By recording the spectrum of C 2 H 2 at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. As for the spectroscopy-determined temperatures, although with a reproducibility better than 10 ppm, we found a systematic deviation of about 800 ppm, which is attributed to 'hidden' weak lines overlapped with the selected transition at 787 nm. Our analysis indicates that it is feasible to pursue a DBT measurement toward the 1 ppm precision using cavity ring-down spectroscopy of a CO line at 1.57 μm.
We reported an experimental fabrication of double-gated (DG) thin-film transistor (TFT) with IGZO recess-channel using a designer photoresist-based thin-film profile engineering approach. In this approach, an organic shadow mask of photoresist (PR) was formed over a p+-Si wafer that was encapsulated by an oxide layer. The lithographically-patterned PR layer is an effective mask for shadowing reactive species during the subsequent deposition steps of IGZO and Aluminum, enabling the formation of IGZO recess-channel and discrete Al source/drain pads at room-temperature. The top-gate or DG configurations with the Si substrate serving as the bottom-gate were investigated. The fabricated DG TFTs show significant improvements in both ION and IOFF as compared with single-gated TFTs. The proposed process scheme is readily applicable to the back-end-of-line of a chip. This work demonstrates the feasibility of IGZO recess-channel TFTs in various gated configurations, enabling a building block for emerging functional devices for More-than-Moore applications.
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