Negligible Electronic Interaction between Photoexcited Electron-Hole Pairs and Free Electrons in Phosphorus-Boron Co-Doped Silicon Nanocrystals - jp7b12313_si_001

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Supporting Information

Rens Limpens1#_{, Minoru Fujii}2_{, Nathan R. Neale}1 _{& Tom Gregorkiewicz}3

1_{National Renewable Energy Laboratory,} 15013 Denver West Parkway, Golden, CO 80401, 303-275-3000, USA. 2_{Department of Electrical and Electronic Engineering, Kobe University,} Rokkodai, Nada, Kobe 657-8501, Japan. 3_{Van der Waals-Zeeman, University of Amsterdam,} Science Park 904, 1098 XH Amsterdam, the Netherlands. # corresponding author: Rens Limpens: rens.limpens@nrel.gov Lorentzian shape of the SiO2 signal in the XRD pattern

The derivation of the average NC size for the co-doped NCs was deduced from an XRD measurement, as shown in Fig. 1c in the main text. To achieve a robust fit of the XRD pattern on the crystalline (111) Si feature we measured the SiO2 signature separately, the data is shown in Fig. S1. The red markers indicate the intrinsic SiO2 signal, perfectly fitted with a Lorentzian fitting curve, enabling us to assign the peak position (angle=21.12) and FWHM (8.52) of the specific feature. These fitting values are subsequently used to fit the total XRD pattern of the co-doped Si NCs and by making use of the Scherrer equation we derived the average NC size, with an estimated fitting precision of ± 0.5 nm.

S2 Fig. S1. Analysis of the SiO2 XRD feature. The red circles represent the XRD signal of a pure SiO2 sample. For clarity we added the XRD pattern of the co-doped Si NC sample in the grey circles. The SiO2 signature could be modeled with a Lorentzian fitting curve with a peak and FWHM of 21.12 and 8.52, respectively, as we display by the red dashed line. These fitting values are used to extract the NC sizes by making use of the Sherrer equation in the main text. Verification of the nonlinear excitation regime By increasing the pump intensity we incite the non-linear excitation regime in which Auger recombination between two (or more) photo-excited e-h pairs dominates the carrier dynamics in the first hundreds of picoseconds. In Figure S2 we present IA traces of the co-doped Si NCs for varying pump powers, for both samples. Upon increasing the excitation density we clearly see a fast Auger component growing in at short time-scales. Verification of the nonlinear excitation regime is shown in the inset where we quantify the A/B ratio for several excitation intensities, with A the IA

S3 magnitude at 1 ps and B the magnitude at 500 ps (as indicated in Figure 2 in the manuscript), just as in Ref. 1. Figure S2. Pump intensity dependence of the IA traces of intrinsic (a) and P-B co-doped

Si NCs (b), derived at λPump = 500 nm and λProbe = 1200 -1350 nm. Main panels) IA

traces for increasing excitation intensities, with point A and B indicating the IA

magnitude at Dt=1 ps and Dt=500 ps, respectively. Insets) A/B ratios as a function of

the relative amount of absorbed photons, verifying the linear excitation regime

(Nabs<<1) for the lowest excitation intensities. The data points in the inset of (b) have

been published in a recent paper,1 _{and only the traces with the highest 5 excitation}

densities have been presented in the main panel of (b).

References

1. Chung, N.X.; Limpens, R.; de Weerd, C.; Lesage, A.; Fujii, M.; Gregorkiewicz, T. Towards practical carrier multiplication: Donor/acceptor co-doped Si nanocrystals in SiO2. Nat.: Light, Sc. Appl. (in submission).