The growth mechanism of silicon nanodots synthesized by sputtering method

Abstract

Silicon quantum dots have been grown on sapphire substrate using a self-assembly method of physical vapour deposition. The samples were fabricated at low sputtering rate and varying experimental conditions. Apparently, the onset of nucleation took place during the first 5 minutes of deposition, followed by a further growth of stable islands so-called nanodots, with the measured radii comparable to the predicted values. Other measurement results confirmed the existence of these dots, including the bandgap energy ~1.80 eV from PL and a 5% at. silicon from EDX. The nucleation parameters were predicted as follows: Free energy change per unit volume Gv ~ -2.4×105Jmol-1; Surface energies per unit area, LN = 1.48Jm-2, NS = 21.6-88.3Jcm-2 and LS = 0.82×10-2Jm-2; Critical energies G* = 6.83×10-16-3.68×10-14?J; Critical radii r* = 20-72nm. This experimental evidence strongly support the early stage growth model of silicon quantum dot deposited on corning glass substrate.