In order to achieve improved convergence, an extra window was added for the 4 nm × 4 nm × 0.5 nm ND system and the 4 nm × 4 nm × 0.5 nm ND system with a large bilayer at z = 1.58 nm and z = 1.88 nm, respectively.
Three additional, 30-ns simulations for z = 1.35 nm, z = 1.5 nm and z = 1.58 nm of the 4 nm × 4 nm × 0.5 nm ND system and for z = 1.8 nm, z = 1.88 nm and z = 1.95 nm of the 4 nm × 4 nm × 0.5 nm ND system with a large bilayer were performed, respectively, in order to reduce the relatively large errors for these windows.
Furthermore, it was found that the designed ND system remained sensitive and robust even when it used raw signals with a relatively low sampling rate, on a fairly narrow time window and even noised signals.
One of the scope was to investigate the crucial internal impact damage and assess the ability of an unconventional ND system (ESPI) in giving right information about non-visual damage generated inside composite laminates subjected to dynamic loads.
These energy differences for the emissive states can be attributed to the different coupling states of the carrier wavefunctions in the present high-density ND system.
This E0 level is possibly due to localization at trap states formed by spatial displacements of wavefunctions of an electron and hole in the ND system.
The difference of the activation energy between different decaying PL components supports the existence of different wavefunctions of the carriers in this high-density ND system.
Higher-energy levels with faster decay times (I2 with τ2, and I3 with τ3) are excited states in the ND system, and the coupling of carrier wavefunctions among NDs can form these excited states.
The lowest energy state associated to the slowest PL component (I1 with τ1) originates from the electron hole pairs that are weakly localized in surface states in individual NDs, which corresponds to the ground state in the present high-density ND system, and the wavefunctions of carriers are localized within one ND.
Further study to test the energetic structure experimentally elucidated here in the Si-ND system is needed using three-dimensional calculations of the carrier wavefunctions based on the actual ND array structure.
