Efficient n-type doping of Si nanocrystals embedded in SiO2 by ion beam synthesis

Abstract

It is shown that co-implantation, with overlapping projected ranges of Si and P or As, followed by a single thermal annealing step is an efficient way to form doped Si nanocrystals (Si-nc's) embedded in SiO2 with diameters of a few nanometers. Atom probe tomography is used to image directly the spatial distribution of the various species at the atomic scale, evidencing that the P and As atoms are efficiently introduced inside the Si nanocrystals. In addition, we report on the influence of the dopant doses on the Si-nc's related photoluminescence as well as on the I(V) characteristics of MOS structures including these Si-nc's.

Density functional theory study on the B doping and B/P codoping of Si nanocrystals embedded in SiO2

“…when a dangling bond exists at the Si/SiO 2 interface. Since dangling bonds often exist at the Si/SiO 2 interface in the real world [55], our current result predicts that B may be routinely found to preferentially occupy the Si/SiO 2 interface region when a Si NC embedded in SiO 2 is doped with B. Khelifi et al [56] and Xie et al [57] have recently demonstrated that this is indeed the case. The existence of a dangling bond at the Si/SiO 2 interface also reduces the values of E f for B in the NC core [ Fig.…”

Thermodynamic stability of high phosphorus concentration in silicon nanostructures

“…The P areal density in the NCs (Φ) is computed by integrating the peak of the 31 P − profiles at the NCs. The ratio Φ/N gives the average number of P atoms trapped within a single NC structure, while dividing by the average number of Si atoms per NC we get the atomic fraction ( percentage) of P within Si NCs:…”

“…This is in striking contrast to theoretical models predicting self-purification phenomena, 5,[37][38][39]49 and experiments far from equilibrium. 15,31,32,47,48 It is worth considering that all the calculations predicting the P solubility in Si NCs consider H-termination of the nanostructures, and they consequently suggest a decrease of the solubility with decreasing cluster size. In our experiment Si NCs are O-terminated accounting for the discrepancy with the calculations and indicating that, also in this case, a significant role of surface termination is played in the equilibrium solubility of dopants at the nanoscale.…”

Ab initio study on the effect of structural relaxation on the electronic and optical properties of P-doped Si nanocrystals

“…In the nanometer-sized regime, it is expected that doping should also be adopted to support the development of a variety of novel devices based on Si nanocrystals (NCs). [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Up to now, doping has been experimentally realized for solid-phase-synthesized Si NCs that are embedded in silicon dioxide (SiO 2 ) 18-20 and gas-phase-synthesized freestanding Si NCs that are passivated by hydrogen. [21][22][23] It has been shown that there exist significant differences in structural, electronic, and optical properties between Si NCs embedded in SiO 2 and those passivated by hydrogen.…”