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This article presents results on flexible high-temperature polycrystalline silicon (FHTPS) thin-film transistor (TFT) fabricated on metal foils. Metal foils eliminate processing temperature constraints which are rather stringent on flexible TFT devices fabricated on plastics and allow high-temperature post-crystallization annealing (PCA). The source/drain (S/D) area of the devices was doped by diffusion with a spin-coated solid source at high temperatures and this process also functioned as PCA to improve the quality of the active undoped area. Solid-phase crystallized TFTs with diffused S/D at 800 °C demonstrate saturation mobility ( $\mu _{SAT}$ ) of 103 cm2/ $\text{V}\cdot \text{s}$ , an ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio of close to 106, a subthreshold swing (SS) of 498 mV/dec, and a threshold voltage ( ${V}_{TH}$ ) of 4.9 V. Technology computer-aided design (TCAD) simulations reveal that parasitic resistance accounts for most of the performance variations of devices diffused at different temperatures when the devices are turned on, and defect density is dominant in the subthreshold and the off regimes. The performance of the fabricated devices suffered only slight changes after 10 000 cycles of bending with 7 mm radius showing their mechanical robustness.

We demonstrated broadband S-band (1460–1530 nm) amplification in Tm3+-doped fluorotellurite glass fibers (TDFTFs) by using a 1400/1570 nm dual-wavelength pump technique. TDFTFs based on TeO2-BaF2-Y2O3 (TBY) glass were fabricated by using a rod-in-tube method. For an input signal power of 0 dBm (or 1 mW), a broadband positive net gain ranging from 3+ doping concentration of ∼4000 ppm, as the pump powers of the 1400 nm and 1570 nm lasers were 1.7 W and 0.14 W, respectively. The corresponding bandwidth for a net gain of >20 dB was ∼66 nm (1458–1524 nm), and the measured saturated output power was ∼24.84 dBm at 1490 nm. In addition, numerical simulation was performed by using the parameters of the TDFTFs and the pump lasers, and the noise figure was calculated to be

Tm3+ doped fluoroaluminate glass fibers are fabricated by using a rod-in-tube method based on AlF3-BaF2-YF3-MgF2-PbF2 glasses. By using a 1400/1570 nm dual-wavelength upconversion pump technique, lasing at ∼2.3 µm is obtained from a 2.3 m long Tm3+ doped fluoroaluminate glass fiber. The measured maximum unsaturated output power is ∼111 mW for a pump power of 1.5/0.14 W at 1400/1570 nm, and the corresponding slope efficiency is ∼11%. The effect of the gain fiber length on lasing at ∼2.3 µm is also investigated. Our results indicate that Tm3+ doped fluoroaluminate glass fibers are promising gain media for constructing ∼2.3 µm fiber lasers.

A new growth method to make highly oriented GaAs thin films on flexible metal substrates has been developed, enabling roll-to-roll manufacturing of flexible semiconductor devices. The grains are oriented in the direction with

Single-crystalline-like thin film GaAs has been grown on epi-ready germanium-buffered flexible metal substrates. The GaAs on flexible substrate has been used to fabricate flexible photovoltaic and flexible photodetector devices. Flexible GaAs photovoltaics on inexpensive substrate addresses the problem with the exorbitant cost of GaAs single crystal wafers that have been used so far. Efficiency levels up to 13.1% have been achieved with GaAs on metal substrate. A 360° field of view is feasible with flexible GaAs photodetectors that is not possible with rigid formats. A responsivity value of 0.8 A/W was obtained at 830 nm that is on par with commercial GaAs photodetectors. The flexible GaAs photodetector exhibits short rise and fall times (less than 0.2 ms), good reproducibility and fully-reversible switching ability. Thin film GaAs on flexible substrates can open up a wide range of applications in flexible electronics where high performance, high power or operation in extreme environments is needed and not feasible with polymer-based flexible electronics.