Investigation of the heterojunction diode properties of aluminium doped and undoped zinc oxide thin films

In this thesis, zinc oxide (ZnO) and Al-doped ZnO (ZnO:Al) solutions prepared with different molar ratios of Al dopant 1%, 2%, 3%, 5% by sol-gel method were deposited on glass substrates by spin coating technique. The effect of Al dopant concentration on the structural, morphological, optical and electrical behavior of ZnO thin films was investigated with X-ray Diffraction, Atomic Force Microscopy, X-ray Photoelectron Spectroscopy, UV-Vis Spectrophotometer and Hall effect measurement. The ZnO and ZnO:Al films exhibited hexagonal wurtzite polycrystal structure with a preferred orientation along (002) direction. ZnO film with high optical transmittance more than 90% was obtained with 3% Al-doped. A minimum resistivity of 5,50 Ωcm was obtained in the 1at.% Al-doped ZnO film. All of the films were determined to have n-type electrical conductivity. n-ZnO/p-Si ve n-ZnO:Al/p-Si heterojunction diode fabricated by n-ZnO and n-ZnO:Al thin films (range of 1–5 at.% Al) have been deposited on p-type Si (100) substrates by sol-gel method. The electrical heterojunction properties were investigated current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The heterojunction diodes showed rectifying current feature behavior like diode. Saturation current, ideality factor, built-in potential and acceptor concentration as electrical parameters of heterojunction diodes were calculated.