Plazma Poli(etilen oksit) Filmlerin Dielektrik Kaybının Kalınlığa Bağlılığı

Plazma poli (etilen oksit) (pPEO) ince film örneklerinin dielektrik özellikleri oda sıcaklığında incelendi. Farklı kalınlıklardaki ince film örnekleri, 5 W plazma boşaltma gücünde plazma destekli fiziksel buhar depozisyonu (PAPVD) tekniği ile elde edildi. Film kalınlıkları 20, 100, 250, 500 nm’dir. Artan film kalınlığı ile dielektrik sabitinin arttığı gözlenmiştir. Dielektrik kayıp ve frekans ilişkisi ile belirlenen relaksasyon zamanları, artan kalınlık ile daha yüksek frekanslara kaymaktadır. Film kalınlığına ilaveten, ısıtma süreçleri bir diğer parametre olarak tanımlandı. Bu amaçla, ince film örnekleri sırasıyla ısıtılmış ve soğutulmuştur. Soğutma sürecindeki dielektrik kaybın maksimum ve minimumunun, ısıtma sürecindeki maksimum ve minimumunun belirlendiği frekanslardan daha alçak frekanslarda meydana geldiği gözlenmiştir. Bu sonuçlar, daha ince filmlerde ölü tabakanın etkisini gösterebilir. Isıtma sürecinden sonra, dielektrik sabiti ve dielektrik kayıp davranışından, çapraz bağlanma yoğunluğunun ısıtma etkisiyle arttığı gözlenmiştir. Bu etki PAPVD'nin ürünü olan serbest radikaller arasında ek tepkimelere neden olabilir. Ayrıca dinamik camsı geçiş sıcaklıkları hesaplandı. Bu sıcaklıklar ölü tabaka yaklaşımı etkisini ispatlamaktadır.

Thickness Dependent Dielectric Loss of Plasma Poly (Ethylene Oxide) Films

Dielectric properties of plasma poly (ethylene oxide) (pPEO) thin film samples were investigated atroom temperature. The thin film samples with different thicknesses were deposited by plasma assistedphysical vapor deposition (PAPVD) technique at 5 W plasma discharge power. The thicknesses were 20, 100,250, 500 nm. It was observed that dielectric constant increases with increasing thickness. The relaxation timesdetermined by dielectric loss-frequency relation, shift toward higher frequencies with increasing thickness. Inaddition film thickness, heating processes were defined as another parameter. By this purpose, thin filmsamples were heated and cooled, respectively. It was observed that maxima and minima of dielectric loss atcooling process take place at lower frequencies in comparison with frequencies at which maxima and minimawere detected at heating process. These results may show the effect of dead layer at thinner films. Afterheating process, it was observed from behavior of dielectric constant and dielectric loss that the crosslinkingdensity increases by heating effect. This effect may cause additional reactions between free radicals which areproduction of PAPVD. Moreover, dynamic glass transition temperatures were calculated. These temperaturesprove the effect of dead layer approximation.

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