Narrow Results

ZnO NWs were grown on Si (111) and Al₂O₃ substrates using MOCVD. ZnO (002) NWs on Si were randomly orientated while the NWs grown on sapphire were mostly vertically aligned as evident from scanning electron microscope images. The c-axis lattice constant corresponding to ZnO (002)/Si(111) demonstrated a dominant peak at 34.47°(2θ) attributed to ZnO along (002) with a FHWM of 0.0948°(θ) with corresponding c and a-lattice axes constants of 5.1996Å and 3.2456Å, respectively. The c-axis lattice constant for ZnO/sapphire was estimated to be 5.205Å resulting in an out of plane strain of only 0.03%. Photoluminescence of ZnO nanowires grown on sapphire shows absorption peaks associated to exciton-exciton recombination and native defect such as zinc interstitial. In the case of NWs grown on Si, only exciton to exciton recombination was observed.

We investigate electron transport between circular graphene quantum dots (CGQDs) and ZnO nanowires (ZnO NWs). This structure can be used as donor and acceptor in hybrid solar cells. We consider circular quantum dots (QDs) and use analytical calculation in order to estimate wavefunctions of GQD and ZnO NWs. After calculating the wavefunctions overlap, we use Marcus relation in order to calculate electron transfer rate. Also, we calculate this transfer rate for CdSe QDs–ZnO NWs system. Results from analytical calculation show that the transfer rate is limited to 10${}^{13}$ s${}^{-1}$. This result is in agreement with experimental results which are reported earlier. Such systems could be suitable for solar cells.