Electro-optic modulators transform electronic signals into the optical domain and are critical components in modern telecommunication networks, RF photonics, and emerging applications in quantum photonics and beam steering. All these applications require integrated and voltage-efficient modulator solutions with compact formfactors that are seamlessly integratable with Silicon photonics platforms and feature near-CMOS material processing synergies. However, existing integrated modulators are challenged to meet these requirements. Conversely, emerging electro-optic materials heterogeneously integrated with Si photonics open a new avenue for device engineering. Indium tin oxide (ITO) is one such compelling material for heterogeneous integration in Si exhibiting formidable electro-optic effect characterized by unity order index at telecommunication frequencies. Here we overcome these limitations and demonstrate a monolithically integrated ITO electrooptic modulator based on a Mach Zehnder interferometer (MZI) featuring a high-performance half-wave voltage and active device length product, VpL = 0.52 V•mm. We show, how that the unity-strong index change enables a 30 micrometer-short pphase shifter operating ITO in the index-dominated region away from the epsilon-bear-zero ENZ point. This device experimentally confirms electrical phase shifting in ITO enabling its use in multifaceted applications including dense on-chip communication networks, nonlinearity for activation functions in photonic neural networks, and phased array applications for LiDAR.

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The rapid chemistry and processing development along with exploring underlying fundamentals [1,2] have increased the performance of perovskite solar cells (PSCs) to over 25%, [3] making them a potential candidate for nextgeneration photovoltaics (PVs). PSCs consist of a photoabsorber film sandwiched between n-type and p-type charge transport films, [4] all shown to be solution processable and thus, fabricable using scalable depositions such as slot die, [5,6] gravure, [7] spray, [8] and inkjet-printing systems [9,10] through automated manufacturing. The deposition of thin films from solutions has been shown for the SnO 2 electron transport layer (ETL), perovskite, and carbon electrodes. After deposition, these layers should undergo drying and possibly an annealing step; thus, the production of PSCs is suitable for automated manufacturing.To realize automated fabrication of PSCs with required control of the printing and IPL annealing processes, we integrated these processes into the "NeXus," a custom-designed system with robotics and motion control capabilities. The NeXus is a novel instrument for flexible multiscale manufacturing, implementing precision robotic assembly, additive manufacturing, and multiscale integration of miniature devices and systems. In addition to a commercial IPL annealing subsystem from Xenon Corporation, USA, the NeXus includes a deposition subsystem, a Pico Pulse Inkjet printhead from Nordson Corporation, USA. Samples move between these subsystems with the help of a custom 6 degree-of-freedom (DOF) robotic positioner, allowing not only fast transport of the samples between the processing tools, but also precise motion control during printing. The NeXus also integrates other manufacturing techniques, such as a dual-head fused deposition modeling (FDM) 3D printing, aerosol jetting, and microassembly. [11][12][13] Furthermore, a novel bonding process has been developed utilizing an ultrasonic vibration technique to embed metal wire in a polymer. [14,15] Slot-die coating is the most studied method for versatile and low-cost scalable deposition of thin-film PSCs, [6,16,17] whereas inkjet printing allows for the deposition of extremely high-resolution features with desired patterns. Inkjet-printing systems utilize thermal or piezoelectric drop-on-demand (DOD) technologies, where the latter produces more uniform size droplets and enables better distribution as a result of rapid

While stress-free and tensile films are well-suited for released in-plane MEMS designs, compressive films are needed for released out-of-plane MEMS structures such as buckled beams and diaphragms. This study presents a characterization of stress on a variety of sputtered and plasma-enhanced chemical vapour deposition (PECVD)-deposited films, including titanium tungsten, invar, silicon nitride and amorphous silicon, appropriate for the field of bistable MEMS. Techniques and strategies are presented (including varying substrate bias, pressure, temperature, and frequency multiplexing) for tuning internal stress across the spectrum from highly compressive (−2300 MPa) to highly tensile (1500 MPa). Conditions for obtaining stress-free films are also presented in this work. Under certain conditions during the PECVD deposition of amorphous silicon, interesting ‘micro-bubbles’ formed within the deposited films. Strategies to mitigate their formation are presented, resulting in a dramatic improvement in surface roughness quality from 667 nm root mean square (RMS) to 16 nm RMS. All final deposited films successfully passed the traditional ‘tape test’ for adhesion.

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Bistable elements are candidate structures for the evolving field of MEMS-based no-power event-driven sensors. In this paper, we present a strategy for producing bistable elements and investigate two compatible bilayer material systems for their realization using MEMS technology. Both bilayer systems leverage thermally-grown silicon dioxide as the principal stress-producing layer and a second material (either polyimide or aluminum) as the main structural layer. Arrays of buckled circular diaphragms, ranging in diameter from 100 μm to 700 μm in 50 μm increments, were fabricated and their performances were compared to modeled and FEA-simulated results. In all cases, the diaphragms buckled when DRIE-released as expected, and their buckled experimental heights were within 9.1% of the theory and 1.8% of the FEA prediction. Interestingly, the smaller diameter structures exhibited a directional bias which we investigate and forecast using FEA. These bistable mechanical elements have the ability to serve as building blocks for no-power threshold-driven smart switches. New contributions to the field include: (a) introduction of a new bistable material system made from aluminum and compressive oxide, (b) investigation of diaphragm diameter size as it related to the phenomena of bistability versus non-bistability, (c) FEA analysis of the critical transition between bistability and non-bistability, and (d) introduction of the ‘dome factor’ term to describe dome quality.

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