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Effect of gamma irradiation dose on the structure and pH sensitivity of ITO thin films in extended gate field effect transistor
摘要： Even though several studies have demonstrated the use of Indium Tin Oxides (ITO) as an extended gate field effect transistor (EGFET), the effect of different doses of gamma radiation on the intrinsic properties of the ITO films has not been considered. This study investigates the effect of gamma irradiation on the structural, optical, morphological and electrical properties as well as pH sensitivity (as an extended gate field effect transistor) of ITO thin films. ITO thin films with thickness of 400 nm were prepared using a radio frequency sputtering technique. The samples were then subjected to various doses of gamma radiation from a Co-60 radio-isotope (0.5 kGy, 1 kGy, 1.5 kGy, and 2 kGy). The structural and morphological changes as well as transmission and absorption of the thin films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Field-Emission Scanning Electron Microscope (FESEM) and UV-Vis spectrophotometry, before and after irradiation. The irradiated ITO thin films were then used as an extended gate field effect transistor to determine its ability to improve sensitivity as pH sensors. The grain size and transmittance in the range 300-900 nm of the ITO films were found to decrease with increasing gamma irradiation dose. In contrast, the uniformity and surface roughness of ITO thin films increased with increasing gamma radiation dose due to the formation of lattice defects. Moreover, the electrical resistance of the thin films increased with increasing dose because of the low current density and high number of surface defects associated with irradiation. The pH sensitivity of the ITO thin films improved after irradiation, possibly due to the concomitant increase in surface roughness with increasing radiation dose. The improvements in the pH sensitivity of ITO thin films after irradiation justify their potential use as pH sensors.
关键词： EGFET,pH sensor,Optical band gap,Gamma irradiation,X-ray diffraction,Indium Tin Oxide,Thin films
更新于2025-09-10 09:29:36
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Achieving enhanced pH sensitivity using capacitive coupling in extended gate FET sensors with various high-K sensing films
摘要： Sensing properties of various high-k sensing membrane, such as SnO2, HfO2, ZrO2, and Ta2O5, in dual gate extended-gate field-effect transistor (EGFET) were investigated. By adapting the dual-gate structure, high sensitivity exceeding the conventional Nernstian limit on sensitivity (59.15 mV/pH at 25 °C) was realized due to capacitive coupling effect. As a results, it was confirmed that dual-gate EGFET with Ta2O5 sensing membrane which has high permittivity shows the highest sensitivity of 478.0 mV/pH as well as excellent hysteresis voltage and drift rate characteristics.
关键词： Glass EG detector,Dual gate poly-Si TFT transducer,High-k membrane,Highest sensitivity,Capacitive coupling,EGFET pH sensor
更新于2025-09-04 15:30:14