A new methodology for the development of miniature photoacoustic trace gas sensors using 3D printing is presented. A near-infrared distributed feedback (DFB) laser is used together with a polymer-based gas cell, off-the-shelf fiber optic collimators, and a microelectromechanical system (MEMS) microphone to measure acetylene at 1532.83 nm. The resonance behavior of the miniature gas cell is analyzed using a theoretical and experimental approach, with a measured resonance frequency of 15.25 kHz and a Q-factor of 15. A minimum normalized noise equivalent absorption of 4.5×10(-9)  W cm(-1) Hz(-1/2) is shown together with a 3σ detection limit of 750 parts per billion (ppb) for signal averaging times of 35 s. The fiber-coupled delivery and miniature cost-effective cell design allows for use in multipoint and remote detection applications.

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T-gates are commonly used in high frequency low noise transistors on III–V materials since they provide a combination of short gate length and low gate resistance. Nanoimprint lithography can produce minimum pattern feature sizes equivalent to those attainable by high resolution electron beam lithography and it has potential advantages in terms of speed and cost. The imprint lithography step must be reliable and compatible with existing device process flows. In this article we describe a bilayer resist imprinting procedure for the fabrication of 120 nm T-gates for high electron mobility transistors. The results of transistor dc characterization are also presented and are similar to those obtained for transistors fabricated on the same material with gates realized by electron beam lithography.

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Tin oxide (SnO(2)) cluster nanowires have been fabricated using atomic clusters as building blocks. Nanowires with widths of less than 100 nm were defined using electron beam lithography followed by deposition of Sn clusters which were subsequently thermally oxidized. The cluster nanowires were used to fabricate field effect transistors. The transistors were n-type and demonstrated a clear size-dependent behaviour. With zero gate bias the narrowest wires were depleted, both the carrier concentration and the conduction quickly increasing with wire width. This behaviour is attributed to the formation of a surface depletion region caused by Fermi level pinning. The width of the depletion region was estimated using the carrier concentration calculated from the transistor threshold voltages. The change in the wire conductance with UV illumination was also investigated. Illumination with 365 nm light increases the conduction by up to 40 times. This is attributed to a combination of an increase in carriers due to photo-desorption of oxygen from the surface of the wires and an increase in the mobility due to a reduction of inter-grain potential barrier height.

As microelectromechnical systems (MEMS) becomes more complex and are produced in even greater numbers it becomes increasingly important to have a full understanding of the mechanical properties of the commonly used MEMS materials. One of the most important properties for MEMS is the Young's modulus. This work describes the direct comparison of two methods often used for measuring the Young's modulus of thin film materials using micro-cantilever test structures: a load-deflection method and a resonant frequency method. The comparison was carried out for a range of materials, different cantilever geometries as well as for single and multilayer materials. It was found that both methods produce results that agree with each other and also agree with the values most often given in the literature.

A method is presented for the fabrication of three-dimensional (3D) structures formed in Hydrogen Silsequioxane (HSQ) by a process of multiple low energy electron beam exposures with a single development step. Structures have been produced consisting of multiple layers of dielectric rods with widths and heights of 150nm and a separation of 1µm in the horizontal plane and 360nm in the vertical direction.