Large-area compatible, solar-blind deep-ultraviolet sensors based on active pixels are demonstrated with CMOS amplifiers based on poly-Si thin-film transistors and Ga ₂ O ₃ thin-film photoresistors. The active pixel configuration sensor enables approximately 40X higher responsivity compared to a discrete sensor, and the CMOS inverter amplifier exhibits a gain of 210 V/V. The Ga ₂ O ₃ -based sensors were integrated on the same substrate depositing the films using magnetron sputtering at room temperature, ensuring its compatibility with large-area applications. The responsivity of discrete Ga ₂ O ₃ sensors was evaluated at different wavelengths in the deep-ultraviolet and visible ranges, and showed a maximum responsivity of 51 A/W for a wavelength of 232 nm, with a deep-ultraviolet to visible light rejection ratio of approximately 10 ² . The active pixel sensor was implemented as flame detector resulting in an output voltage signal of up to 2 V when the system was exposed to a flame under regular background illumination conditions.

In recent years $\beta $ -Ga ₂ O ₃ thin films and crystals have gained attention as excellent candidates for transparent and high-power applications due to its wide band gap (4.6 – 4.9 eV) and large breakdown field (~8 mV/cm). However, $\beta $ -Ga ₂ O ₃ single crystals and highly crystalline $\beta $ -Ga ₂ O ₃ thin films require high temperature, long processing times and, often, expensive tools that limit integration with other technologies. Amorphous Ga ₂ O ₃ has not been studied as intensely as $\beta $ -Ga ₂ O ₃ and mostly metal-semiconductor-metal (MSM) structures and diodes using this material have been reported. In this paper, we discuss a simple and economical method to fabricate thin film transistors (TFTs) based on un-doped amorphous Ga ₂ O ₃ thin films deposited at room temperature by magnetron sputtering. Control of the Ga ₂ O ₃ thin films resistivity over a wide range is demonstrated by controlling the deposition power and pressure. The TFTs show a threshold voltage ( $\text{V}_{{\mathrm {T}}}$ ) of 0.92 V, saturation mobility ( $\mu _{{\mathrm {sat}}}$ ) of 0.511 cm ² / $\text{V}\cdot \text{s}$ and subthreshold slope (SS) of 83.62 mV/dec. More importantly, these devices have been evaluated as phototransistors, which has not been intensely studied yet. The phototransistors tested under DUV radiation exhibited a rejection ratio UV-Visible of 10 ³ and responsivity of $10^{2}\text{A}$ /W ( $\text{V}_{{\mathrm {G}}} =0$ V) and 10 ⁴ A/W ( $\text{V}_{{\mathrm {G}}} =6$ V), gain of 10 ³ , specific detectivity of 10 ¹⁵ Jones and a photosensitivity of 10 ⁷ .

We propose the use of polysilicon thin-film circuits to develop charged particle and neutron detection systems. We detail the methodology to design, fabricate, and implement polysilicon preamplifiers with the requirements for radiation detectors. We demonstrate the combination of polysilicon electronics with Si photodiodes to resolve the spectral response of a ²¹⁰ Po alpha source and demonstrate for the first time neutron detection capabilities. Also, we present the first implementation of a full thin-film radiation detection system using CdS/CdTe detectors and a polysilicon thin-film transistor for single-event charged particle detection.

In this work, it is presented a unified model to integrate a radiation detector on a single chip using TFTs-based amplifiers, to fabricate a low-cost thermal neutron detector system. The model is based on the current-voltage experimental measurements of the CdS/CdTe detector and CMOS Si-Poly TFTs technology. Parameters obtained by I-V and C-V analysis were introduced into Smart SPICE to design the amplifiers. The output voltage was simulated for a neutron capture event. Three amplification topologies were studied, obtaining an output voltage in the range of 180 to 260 mV with a generated photocurrent pulse around 3.5 lA, which is high enough to be interfaced with a microcontroller. The neutron detector is integrated into TFT amplifiers with a gain of around 50 dB and bandwidth of 4.7 MHz at -3 dB.