During the synthesis of ZnSe nanowires various point and extended defects could form, leading to observed stacking faults and twinning defects, and strong defect related emission in photoluminescence spectra. Here, the development of a simple thermodynamic model for estimating the defect concentration in ZnSe nanowires grown under varying Se vapour pressure and for explaining the results of the experimental findings was reported. Positron annihilation spectroscopy was used successfully for the first time for nanowires and the results support predictions from the defect model as well as agreeing well with structural and optical characterization results. Under very high Se vapour pressure, Se nodules were observed to form on the side-walls of the nanowire, indicating that beyond a limit, excess Se will begin to precipitate out of the liquid alloy droplet in the vapour–liquid–solid growth of nanowires.

Defect Studies of ZnSe Nanowires. U.Philipose, A.Saxena, H.E.Ruda, P.J.Simpson, Y.Q.Wang, K.L.Kavanagh: Nanotechnology, 2008, 19[21], 215715 (6pp)