Electrical Characterization of n-type doped metal oxide/p-type Si Photosensitive Heterojunction

Abstract

The n-type 1.5% Ge doped WOx thin film was deposited on Al/p-type Si wafer using the Physical Vapour Deposition (PVD) technique and Al/Si/WOx(%1.5Ge) p-n junction was fabricated. The surface properties of the thin film layer were examined by scanning electron microscopy (SEM) and it was generally observed that the layer had a smooth structure with various size particles grown on surface. In addition, the elemental composition of the thin film was examined by Energy dispersive X-ray spectroscopy (EDS), and it was observed that all detected elements showed a homogeneous distribution at the rates of 96.4% W, 1.5% Ge and 2.2% O. In order to examine the electrical properties of the fabricated heterojunction, Ag rectifier contacts were grown on the active layer surface by the PVD method. As a result, I-V measurements of Al/p-Si/WOx(1.5%Ge)/Ag heterojunction was performed under dark and various light intensities in the potential range of ±4V. Thus, diode parameters such as series resistance, diode ideality factor, barrier height and reverse saturation current were determined by using different methods. It is observed that the series resistance is between 70-10Ω, the diode ideality factor is between 14.1 and 3.9, the barrier height is between 0.54-0.15eV and the reverse saturation current is between 1.34x10-4 A-1.1x10-3 A. The series resistance of the fabricated diode decreased with the increase of the light intensity, and the diode approached the ideal. In addition, the ten times increase in reverse saturation current with light intensity indicates that the fabricated heterojunction exhibits typical photodiode behaviour.

Keywords

• Photodiode
• metal oxide semiconductor
• I-V
• heterojunction
• p-n junction

Işığa Duyarlı n-tipi Katkılı Metal oksit/p-tipi Si Heteroekleminin Elektriksel Karakterizasyonu

Abstract

n-tipi %1.5 Ge katkılı WOx tabakası Al/p-tipi Si üzerine Fiziksel Buhar Biriktirme (FBB) yöntemi kullanılarak büyütülmüştür ve Al/Si/WOx(%1.5Ge) p-n eklemi elde edilmiştir. İnce film tabakasının yüzey özellikleri SEM ile incelenmiş ve tabakanın genel olarak pürüzsüz bir yapıya sahip olduğu görülmüştür. Ayrıca tabakayı oluşturan elementlerin dağılımı Enerji dağılımlı X-ray spektroskopisi (EDX) ile incelenmiş %96.4 W, %1.5 Ge ve %2.2 O oranlarında homojen bir şekilde dağılım gösterdikleri görülmüştür. Üretilen heteroeklemin elektriksel özelliklerinin incelenebilmesi için aktif tabaka yüzeyine yine FBB yöntemiyle Ag doğrultucu kontakları alınmıştır. Sonuç itibariyle Al/Si/WOx(%1.5Ge)/Ag p-n ekleminin ±4V potansiyel aralığında, karanlık ve farklı ışık şiddetlerinde I-V ölçümleri yapılmış, seri direnç, diyot idealite faktörü, engel yüksekliği, ters doyma akımı gibi diyot parametreleri farklı yöntemler kullanarak incelenmiştir. Seri direnç değerlerinin 70-10Ω arasında, diyot idealite faktörünün 14.1 ile 3.9 arasında, engel yüksekliğinin 0.54-0.15eV ve ters doyma akımının 1.34x10-4A-1.1x10-3A arasında değerler aldığı görülmüştür. Işık şiddetinin artmasıyla ürettiğimiz diyotun seri direnci azalmış diyot ideale yaklaşmıştır. Ayrıca ters doyma akımının ışık şiddetiyle on kat artması ürettiğimiz heteroeklemin tipik fotodiyot davranışı sergilediğinin göstergesidir.

Keywords

• Fotodiyot
• metal oksit yarıiletken
• I-V
• heteroeklem
• p-n eklemi

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