This work reports the development of arrays of infrared sensors (microbolometers) using a hydrogenated polymorphous silicon–germanium alloy (pm-Si_xGe_1-x:H). Basically, polymorphous semiconductors consist of an amorphous semiconductor matrix with embedded nanocrystals of about 2–3 nm. The pm-Si_xGe_1-x:H alloy studied has a high temperature coefficient of resistance (TCR) of 4.08%/K and conductivity of 1.5 × 10⁻⁵ S∙cm⁻¹. Deposition of thermosensing film was made by plasma-enhanced chemical vapor deposition (PECVD) at 200 °C, while the area of the devices is 50 × 50 μm² with a fill factor of 81%. Finally, an array of 19 × 20 microbolometers was packaged for electrical characterization. Voltage responsivity values were obtained in the range of 4 × 10⁴ V/W and detectivity around 2 × 10⁷ cm∙Hz^1/2/W with a polarization current of 70 μA at a chopper frequency of 30 Hz. A minimum value of 2 × 10⁻¹⁰ W/Hz^1/2 noise equivalent power was obtained at room temperature. In addition, it was found that all the tested devices responded to incident infrared radiation, proving that the structure and mechanical stability are excellent.

In this paper, we have fabricated and characterized uncooled microbolometers using as infrared element intrinsic amorphous silicon-germanium films with embedded nanocrystals with a dimension in the range of ~2-4 nm. The presence of nanocrystals in the amorphous films reduces the density of defects, improves the transport properties, and specially improves the films stability against radiation. On the other hand, the combination of silicon and germanium in one alloy allows to improve the film conductivity and the temperature coefficient of resistance (TCR), without the necessity of perform doping. Large values of TCR have been demonstrated in the microbolometers, as large as -6.6% K ^-1 , which in fact is the largest value reported for this kind of devices, and consequently large detectivity values were obtained in the reported devices (2 × 10 ⁹ cmHz ^1/2 W ^-1 ).

Energy harvesters are autonomous systems capable of capturing, processing, storing, and utilizing small amounts of free energy from the surrounding environment. Such energy harvesters typically involve three fundamental stages: a micro-generator or energy transducer, a voltage booster or power converter, and an energy storage component. In the case of harvesting mechanical vibrations from the environment, piezoelectric materials have been used as a transducer. For instance, PZT (lead zirconate titanate) is a widely used piezoelectric ceramic due to its high electromechanical coupling factor. However, the integration of PZT into silicon poses certain limitations, not only in the harvesting stage but also in embedding a power management electronics circuit. On the other hand, in thermoelectric (TE) energy harvesting, a recent approach involves using abundant, eco-friendly, and low-cost materials that are compatible with CMOS technology, such as silicon-based compound nanostructures for TE thin film devices. Thus, this review aims to present the current advancements in the fabrication and integration of Si-based thin-film devices for TE energy harvesting applications. Moreover, this paper also highlights some recent developments in electronic architectures that aim to enhance the overall efficiency of the complete energy harvesting system.