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  • Küçük Resim
    Öğe
    Al/Al2o3/P-Si yapısının Co gaz algılama özellikleri
    (Gazi Üniversitesi, 2015) Karaduman, Irmak; Demirel, Nevin; Yıldız, Dilber Esra; Acar, Selim
    Bu çalışmada Al/Al2O3/p-Si yapısının gaz algılama özellikleri incelenmiştir. Al2O3 metal oksit yapısı atomik tabaka biriktirme (ALD) metoduyla üretilmiştir. Üretilen yapının farklı sıcaklıklar (300-450K) ve farklı CO gaz konsantrasyonlarında (50-2000 ppm) gaz algılama özellikleri incelenmiştir. Artan sıcaklık ve gaz konsantrasyonuyla duyarlılıklarda artış gözlenmiştir. Elde edilen grafikler göstermektedir ki gaz molekülleri ile numune yüzeyi arasında yük alışverişine dayalı bir etkileşme vardır. Ayrıca tepki ve geri dönüş süreleri sırasıyla 11 ve 16 s olarak hesaplandı.
  • Küçük Resim
    Öğe
    Atomik Tabaka Biriktirme Metodu ile Üretilen HfO2 Tabanlı Sensörlerin Hidrojen Gaz Algılama Özelliklerinin İncelenmesi
    (Gazi Univ, 2016) Karaduman, Irmak; Barin, Özlem; Yıldız, Dilber Esra; Acar, Selim
    Fossil fuels can very quickly be exhausted condition and thus leave harmful residues such as CO 2 environment clean and reliable use of the H-2 gas as the energy source of the future are expanded in various fields. In this case, the new research on the rapidly expanding field of applications and 112 gas sensor causes the increase. In this study, HfO2 thin films are grown on the p-Si by Atomic Layer Deposition (ALD) method and HfO2/p-Si thin film was produced. HfO2/p-Si structure is grown by Atomic Layer Deposition method and hydrogen gas sensing properties were investigated. Produced sample at different temperatures (30 degrees C-180 degrees C) and at different gas concentrations (1000ppm-4000ppm) as a function of time is investigated with measuring the electrical properties. Measurement results show that HfO2/p-Si thin films produced by ALD can be used as low temperatures hydrogen gas sensors.
  • [ X ]
    Öğe
    CO2 gas detection properties of a TIO2/Al2O3 heterostructure under UV light irradiation
    (Institute of Physics Publishing, 2015) Karaduman, Irmak; Demir, Mehmet; Yıldız, Dilber Esra; Acar, Selim
    Al/TiO2/p-Si and Al/TIO2/Al2O3/p-Si samples were prepared using the atomic layer deposition method (ALD) and their gas sensing properties were investigated. The electrical properties of the samples were studied using a two probe method in the temperature range 25-230 degrees C and at room temperature UV conditions. The TiO2/Al2O3 heterojunction sample exhibited an excellent gas sensing response to CO2 gas at room temperature and improved the effect of UV light irradiation. The results showed that heterostructures helped to improve the gas sensor properties, affected the sensing at room temperature and thus guided the design of photocatalysts. The TiO2/Al2O3 heterojunction prepared using this method can be used as a material for semiconductor gas sensors detecting poisonous gases like CO2 at room temperature with high sensitivity and selectivity.
  • [ X ]
    Öğe
    The effect of ultraviolet irradiation on the ultra-thin HfO2 based CO gas sensor
    (American Institute of Physics Inc., 2015) Karaduman, Irmak; Barin, Özlem; Yıldız, Dilber Esra; Acar, Selim
    In this work, an effort has been made to fabricate ultrathin HfO2/Al2O3 sample by atomic layer deposition method for the fast detection of CO gas at room temperature. The effect of the operating temperature and the UV light on the gas sensing characteristics has been studied. We investigated the optimum operating temperature for the sample by sensing 25 ppm CO and CO2 gases from room temperature to 150 °C for 10 °C steps. The maximum response was obtained at 150 °C for both gases in the measurement temperature range. Also, the photoresponse measurements clearly show the effect of UV light on the sample. At room temperature, sensor showed superior response (14%) for 5 ppm CO gas. The response time of sensor is 6 s to 5 ppm CO gas concentration. The ultrathin HfO2 based sample shows acceptable gas sensitivity for 5 ppm CO gas at room temperature under UV light irradiation. © 2015 AIP Publishing LLC.
  • [ X ]
    Öğe
    UV light activated gas sensor for NO2 detection
    (Elsevier Ltd, 2014) Karaduman, Irmak; Yıldız, Dilber Esra; Sincar, Mehmet M.; Acar, Selim
    In the present study, UV light activated gas sensor was investigated for Al/Al2O3/p-Si and Al/TiO2/Al2O3/p-Si samplesby atomic layer deposition method (ALD). Generally, in order to obtain the sensing performance, traditional metal oxide semiconductor gas sensors are operated at 100-400 °C. However, this temperature range limits their applications to flammable gases, and causes high power consumption. It is important to note that sensing performance experiments should have been performed at room temperature. With the support of UV light, gas sensors do not need to be heated and they can work at room temperature easily. For this purpose, electrical measurements have been performed on sensing performance with and without UV irradiation for dedection of NO2 gas. With the help of UV irradition, we obtained good sensitivity at the room temperature for Al/TiO2/Al2O3/p-Sistructure but under the same conditions no result was obtained for Al/Al2O3/p-Si structure. Without UV irradiation, there was no sensitivity for both.We observed that increasing of sensitivities at the room temperature show a direct effect of the light on the adsorbed oxygen ions. According to the relation of photocatalytic reaction and photoactivated gas sensing process, we concluded that TiO2 might be an acceptable sensor for detection of nitrogen dioxide (NO2) at room temperature under UV illumination.