B-DOPING EFFECT ON GAS SOURCE SI-MBE GROWTH - A COMPARISON OF B2H6 GAS DOPING AND HBO2 KNUDSEN CELL DOPING

In Si2H6 gas source Si-MBE, B doping is achieved using HBO2 Knudsen cell or B2H6 gas dopant. B doping effect on gas source Si-MBE growth was studied for these two different doping sources. At high B doping using HBO2 cell, RHEED intensity oscillation was found to extinguish. This is thought to be due to the scattering for Si2H6 surface migration by B adsorbates from HBO2 cell on a growing surface. In fact, RHEED oscillation extinguished for B adsorption of 0.15 monolayer on Si(100) surfaces, whereas the oscillation continued on Si(111) square-root 3 x square-root 3-B in which B occupies a subsurface site under the top layer. On the other hand, RHEED oscillation did not extinguish in B2H6 gas doping. This is because B2H6 is incorporated into the epitaxial layer via the same process as Si2H6.