Structural and electrical properties of trimethylboron-doped silicon nanowires

Trimethylboron (TMB) was investigated as a p-type dopant source for the vapor-liquid-solid growth of boron-doped silicon nanowires (SiNWs). The boron concentration in the nanowires was measured using secondary ion mass spectrometry and results were compared for boron-doping using TMB and diborane (B ₂H ₆) sources. Boron concentrations ranging from 1 × 10 ¹⁸ to 4 × 10 ¹⁹ cm ^-3 were obtained by varying the inlet dopant/SiH ₄ gas ratio. TEM characterization revealed that the B ₂H ₆-doped SiNWs consisted of a crystalline core with a thick amorphous Si coating, while the TMB-doped SiNWs were predominantly single crystal even at high boron concentrations. The difference in structural properties was attributed to the higher thermal stability and reduced reactivity of TMB compared to B ₂H ₆. Four-point resistivity and gate-dependent conductance measurements were used to confirm p-type conductivity in the TMB-doped nanowires and to investigate the effect of dopant concentration on nanowire resistivity.