Structural and optical properties of high quality ZnO films on Si grown by atomic layer deposition at low temperatures

To grow high quality ZnO films on silicon substrates, two-step growth at low temperatures has been carried out using an atomic layer deposition system: ZnO buffer layer growth on Si(111) at 180 ∘C and main layer growth over the buffer at 270 ∘C. The ZnO films on the ZnO buffer/Si(111) were highly c-axis oriented and showed a more intense (0002) peak than those on the Si without a buffer layer. The peak intensity of the (0002) plane increased with the buffer layer thickness (tb) and showed the best crystalline quality at tb=33.1 nm. Photoluminescence measurements also showed a strong UV emission at 380 nm from the ZnO/ZnO buffer (33.1 nm)/Si. Most importantly, the two-step growth technique enables the growth of high quality ZnO films on large and cheap silicon substrates.