Optical and electrical properties of Ga-doped ZnO nanorod arrays fabricated by catalyst-free thermal evaporation

Ga-doped ZnO nanorod arrays with different Ga dopant content (Ga/Zn varied from 0 to 0.8 in the source mixtures) were fabricated by catalyst-free thermal evaporation on p-silicon substrate. The morphology, structure, optical and electrical properties were investigated. The results show that well-aligned array morphologies of single crystalline wurtzite ZnO nanorod with different Ga content are grown preferentially in the c-axis direction. Room-temperature photoluminescence (PL) spectrum of the arrays exhibited unique strong and sharp UV emission band at 380 nm. It reveals a low concentration of oxygen vacancies in the ZnO nanorods and their high optical quality. A p-n diode structure with Ga-doped ZnO nanorods grown on p-Si displayed excellent rectifying behaviors by the I-V characteristics. The conductivity can be largely improved when Ga content (Ga/Zn atom ratio) varied from 0.1 to 0.2 and reached a best electrical property when Ga/Zn is 0.5.