B-doped Si(001) grown by gas-source molecular-beam epitaxy from Si ₂H₆ and B₂H₆:B incorporation and electrical properties

B-doped Si(001)2×1 films were grown on Si(001) substrates by gas-source molecular beam epitaxy using Si₂H₆ and B ₂H₆. B concentrations C_B (5×10 ¹⁶-5×10¹⁹ cm^-3) were found to increase linearly with increasing flux ratio J_B2H₆/J _Si2H₆ (9.3×10^-5-2.5×10 ^-2) at constant film growth temperature T_s (600-950°C) and to decrease exponentially with 1/T_s at constant J _B2H₆/J_Si2H₆ ratio. The B ₂H₆ reactive sticking probability ranged from ≅6.4×10^-4 at T_s=600°C to 1.4×10 ^-3 at 950°C. The difference in the overall activation energies for B and Si incorporation at T_s=600-950°C is ≅0.34 eV. A comparison of quantitative secondary-ion mass spectrometry (SIMS) and temperature-dependent Hall-effect measurements showed that B was incorporated into substitutional electrically active sites over the entire B concentration range investigated. SIMS B depth profiles from modulation-doped samples were abrupt with no indication of surface segregation to within the instrumental resolution limit and initial δ-doping experiments were carried out. Structural analysis by in situ reflection high-energy electron diffraction combined with post-deposition high-resolution plan-view and cross-sectional transmission electron microscopy showed that all films were high-quality single crystals with no evidence of dislocations or other extended defects. Temperature-dependent (20-300 K) hole carrier mobilities were equal to the best reported bulk Si:B values and in good agreement with theoretical maximum values.