The electrothermal behavior of gallium nitride (GaN) HEMTs has been simulated by using a hybrid approach in which the problem is solved by coupling together an effective model (for the electrical part) and a 3-D finite element model (for the thermal part). The effective model relies on the estimation of the channel current at different temperatures in the absence of thermal gradients. This regime occurs in real devices only during the very initial stage of bias pulses, when self-heating effects are not yet developed, for time intervals shorter than 1 ns. Virtual output electrical characteristic, in which self-heating effects are negligible, have been derived from pulsed measurements of the electrical output characteristics and electrothermal transient simulations. The maximum temperature because of self-heating evaluated by using the virtual output characteristic are substantially higher than those obtained using the short time-pulsed measurements directly. The results have been validated by a comparison with temperature measurements obtained using Raman thermography. This approach has proven to be numerically very efficient and fast, allowing the analysis of realistic complex structures and circuits.

Sustainable green electronics is increasingly needed for a multitude of new applications that will fill daily life in the coming decades.

In the last few years, most applications in the field of light sensing have required devices able to detect light intensities as low as pW/cm ² . At the same time, the rise of organic-based sensors is meeting no stops because of the desired properties that organic materials provide, like flexibility, lightweight, low cost, and low temperature processability. Low-intensity light signal detectors are growing in a huge number of fields: in prostate cancer treatment, modern proton therapy is requiring the detection of very low light intensities generated by scintillators that convert the proton flux into a light signal; moreover, in robotics, the most recent products need to detect light both in the sunlight and at the nighttime when the illumination intensity is lower. Here, we report on a flexible organic phototransistor (OPT) with impressive low-light detection, with a limit of detection (LoD) down to 28 pW/cm ² . The OPT works reliably in different environments, acting at low polarization bias down to −1 V. These results show the perspective of a new class of light detectors based on a low-cost manufacturing process for flexible applications.

The electrical performance of organic thin-film transistors (OTFTs) based on DNTT as the semiconductor active layer (DNTT, which stands for dinaphtho [2,3-b:2',3'-f] thieno [3,2-b] thiophene) is investigated and related to the structural properties of the organic films grown on SiO₂ and Cytop substrates. Conventional current-voltage measurements and high-sensitivity low-frequency measurements show a lower mobility and correspondingly higher defect density for DNTT/SiO₂ devices. Morphological and structural characterizations of DNTT films grown on the two dielectrics were performed using atomic force microscopy (AFM) and X-ray diffraction (XRD), revealing a highly ordered crystalline structure. Consistent with DFT simulation results, morphological analysis shows that the semiconductor films are layered, with DNTT molecules arranged with their longest axis perpendicular to the substrate. However, in only DNTT/SiO₂ films, some molecules were found to be ordered and arranged parallel to the substrate. This "horizontal" orientation causes differences in charge transport properties in the semiconductor films grown on SiO₂, reducing the field-effect mobility. TCAD simulations indicate that this horizontal molecular orientation can be modeled as highly defective regions at semiconductor grain boundaries, consistent with low-frequency noise measurement results.

We report on a wearable, human tissue-equivalent, real-time dosimeter designed to quantitatively monitor radiation absorbed by patients during cancer treatments. The fully organic device has been characterized under actual clinical conditions using a high-energy proton beam and an anthropomorphic phantom, with the aim to simulate a prostate cancer proton therapy treatment. We achieved a full control over the dosimeter operation, and we verified its linear response with the received dose. We demonstrate that, by a proper functionalization of the polysiloxane-based scintillator, it is possible to target the effective detection of different kinds of ionizing radiation. Specifically, besides protons, we develop a device able to detect thermal neutrons, targeting its use during Boron Neutron Capture Therapy. This work demonstrates how organic indirect detectors can be considered a universal radiation detecting platform able to monitor in real time and in situ the dose absorbed by patients during cancer treatments under different kinds of radiation.