{001} loops in silicon unraveled

Abstract

By using classical molecular dynamics simulations and a novel technique to identify defects based on the calculation of atomic strain, we have elucidated the detailed mechanisms leading to the anomalous generation and growth of {001} loops found after ultra-fast laser annealing of ion-implanted Si. We show that the building block of the {001} loops is the very stable Arai tetra-interstitial [N. Arai, S. Takeda, M. Kohyama, Phys. Rev. Lett. 78, 4265 (1997)], but their growth is kinetically prevented within conventional Ostwald ripening mechanisms under standard processing conditions. However, our simulations predict that at temperatures close to the Si melting point, Arai tetra-interstitials directly nucleate at the boundaries of fast diffusing selfinterstitial agglomerates, which merge by a coalescence mechanism reaching large sizes in the nanosecond timescale. We demonstrate that the crystallization of such agglomerates into {001} loops and their subsequent growth is mediated by the tensile and compressive strain fields that develop concurrently around the loops. We also show that further annealing produces the unfaulting of {001} loops into perfect dislocations. Besides, from the simulations we have fully characterized the {001} loops, determining their atomic structure, interstitial density and formation energy.

Prediction of the evolution of defects induced by the heated implantation process: Contribution of kinetic Monte Carlo in a multi-scale modeling framework

“…In Fig. 6, the KMC model calibrated with energy differences between I n and I n−1 closer to the one calculated in [6] (in Fig. 5) results in the formation of {311} for the 500 °C case and DLs in RT and 150 °C cases (Fig.…”

“…(section III-B). For high temperature implantation (500 °C), a full KMC simulation was performed based on the results of both molecular dynamics (MD) simulation [6] and own density functional theory (DFT) calculations for a detailed calibration of interstitial clusters (Section III-C and III-D).…”

“…On the other hand in the RT and 150 °C implantations, amorphous pockets do not recombine totally and are less likely to form in stable SMICs as-implanted. SMICs have been the subject of several atomic scale investigations in the literature [6][7] [8]. Two kinds of SMICs have been identified: the chain-like defects type, known as a precursor of {311} [8] and the Arai type whose structure is described in [7].…”

“…Figure5: Difference in formation energies of clusters I n and I n−1 as implemented in the KMC (blue), calculated for the Arai SMIC family using MD[6] (green) and as they were implemented in this work to simulate {311} defects in 500 °C implantation using KMC (red).…”

Clusters of Defects as a Possible Origin of Random Telegraph Signal in Imager Devices: a DFT based Study

“…First, 14 interstitial atoms (14-I) have been randomly placed in a box of 512 crystalline silicon atoms governed by a Tersoff interatomic potential. 14 appears to be one of the most relevant intermediate number between the 4-I structure [28] (and its multiples 8-I, 12-I [29]) that is too stable to change its atomic structure at ambient temperature, and the apparition of the rodlike structures [30] that required a huge number of interstitial atoms. Other cluster sizes could also be used without changing the conclusions.…”