Hyperdoping silicon nanocrystals (Si NCs) to a concentration exceeding the solubility limit of a dopant may enable their novel applications. Here, the successful hyperdoping of Si NCs with boron (B) and phosphorus (P) is demonstrated, which are the most important dopants for Si. Despite the hyperdoping, the diamond structure of Si NCs is hardly modified. There are both electrically active B and P in hyperdoped Si NCs. It is proposed that the hyperdoping is made possible mainly by the kinetics in the nonthermal plasma synthesis of Si NCs. Collision between Si NCs and B or P atoms and the binding energy of B or P at the NC surface are critical to the understanding on the differences in the doping efficiency and dopant distribution between B and P. B‐hyperdoping‐induced tensile stress needs to be taken into account in the investigation on the doping and oxidation of Si NCs.

Technologically important low-resistivity bulk Si has been usually produced by the traditional Czochralski growth method. We now explore a novel method to obtain low-resistivity bulk Si by hot-pressing B- and P-hyperdoped Si nanocrystals (NCs). In this work bulk Si with the resistivity as low as ∼ 0.8 (40) mΩ•cm has been produced by hot pressing P (B)-hyperdoped Si NCs. The dopant type is found to make a difference for the sintering of Si NCs during the hot pressing. Bulk Si hot-pressed from P-hyperdoped Si NCs is more compact than that hot-pressed from B-hyperdoped Si NCs when the hot-pressing temperature is the same. This leads to the fact that P is more effectively activated to produce free carriers than B in the hot-pressed bulk Si. Compared with the dopant concentration, the hot-pressing temperature more significantly affects the structural and electrical properties of hot-pressed bulk Si. With the increase of the hot-pressing temperature the density of hot-pressed bulk Si increases. The highest carrier concentration (lowest resistivity) of bulk Si hot-pressed from B- or P-hyperdoped Si NCs is obtained at the highest hot-pressing temperature of 1050 °C. The mobility of carriers in the hot-pressed bulk Si is low (≤  ∼ 30 cm-2V-1s-1) mainly due to the scattering of carriers induced by structural defects such as pores.