Principal Component Analysis-Assisted Detection of Toxic Chemicals Using Atomic Layer Deposition-Grown Zinc Oxide Thin Films

Abstract

In this study, a highly sensitive and selective gas sensor was developed for detecting hazardous analytes, including ethanol, acetone, hydrogen sulfide (H2S), and hydrogen cyanide (HCN). ZnO thin films were deposited as the sensing layer using atomic layer deposition (ALD), while Au interdigitated electrodes with 5 µm width and spacing were fabricated on SiO2/Si substrates via photolithography. The fabricated sensor exhibited a sensitive response to the target gases even at part-per-billion (ppb). However, it was observed that as the operating temperature decreases, the sensor signal's noise level increases. Additionally, the recovery time for the sensor to return to its baseline value after gas exposure was significantly affected by the operating temperature. The detection limits for ethanol, acetone, H2S, and HCN were 14.6, 35, 115, and 115 ppb, respectively, confirming the sensor's ability to detect all analytes at concentrations well below their threshold limit values. Principal Component Analysis (PCA) revealed well-separated clusters for each analyte, particularly for ethanol and acetone, suggesting that the sensor can effectively discriminate between these two gases. These results demonstrate the sensor’s excellent sensitivity and selectivity supporting its potential for real-time monitoring of toxic gases in environmental and industrial applications.

Keywords

• Atomic layer deposition
• zinc oxide
• thin film
• gas sensor
• principal component analyses

Atomik Katman Biriktirme Yöntemiyle Üretilmiş Çinko Oksit İnce Filmler Kullanılarak Temel Bileşen Analizi Destekli Toksik Kimyasal Tespiti

Abstract

Bu çalışmada, etanol, aseton, hidrojen sülfür (H₂S) ve hidrojen siyanür (HCN) gibi tehlikeli analitlerin tespiti için yüksek hassasiyetli ve seçici bir gaz sensörü geliştirilmiştir. ZnO ince filmleri, sensörleme katmanı olarak atomik katman biriktirme (ALD) yöntemiyle depo edilmiş, 5 µm genişlik ve aralığa sahip Au interdijit elektrotlar ise SiO₂/Si alt tabakalara fotolitografi ile üretilmiştir. Üretilen sensör, hedef gazlara parçacık başına milyar (ppb) seviyesinde bile hassas bir yanıt göstermiştir. Ancak, çalışma sıcaklığı düştükçe sensör sinyalinin gürültü seviyesinin arttığı gözlemlenmiştir. Ayrıca, gaz maruziyetinden sonra sensörün temel değerine geri dönme süresi, çalışma sıcaklığından önemli ölçüde etkilenmiştir. Etanol, aseton, H₂S ve HCN için tespit limitleri sırasıyla 14,6; 35; 115 ve 115 ppb olarak bulunmuş ve bu sonuç sensörün tüm analitleri eşik değerlerinin çok altında tespit edebildiğini doğrulamıştır. Temel Bileşen Analizi (PCA), her bir analit için iyi ayrılmış kümeler ortaya koymuş, özellikle etanol ve asetonda sensörün bu iki gazı etkin bir şekilde ayırt edebileceğini göstermiştir. Bu sonuçlar, sensörün mükemmel hassasiyet ve seçiciliğe sahip olduğunu ve çevresel ve endüstriyel uygulamalarda toksik gazların gerçek zamanlı izlenmesi için potansiyelini desteklediğini göstermektedir.

Keywords

• Atomik Katman Biriktirme
• Çinko Oksit
• İnce Film
• Gaz Sensörü
• Temel Bileşen Analizi

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