SI(001)2X1 GAS-SOURCE MOLECULAR-BEAM EPITAXY FROM SI2H6 - GROWTH-KINETICS AND BORON DOPING

The growth rates R(Si) of Si films deposited on Si(001)2 X 1 from Si2H6 by gas-source molecular-beam epitaxy were determined as a function of temperature T(s) (500-950-degrees-C) and impingement flux J(Si2H6) (0.3-7.7 X 10(16) cm-2 s-1). R(Si) (T(s), J(Si2H6)) curves were well described using a model, with no fitting parameters, based upon dissociative Si2H6 chemisorption followed by a series of surface decomposition reactions with the rate-limiting step being first-order hydrogen desorption from Si monohydride. The zero-coverage Si2H6 reactive sticking probability in the impingement-flux-limited growth regime was found to be 0.036, more than two orders of magnitude higher than that for SiH4. B doping concentrations (C(B) = 5 X 10(16) - 3 X 10(19) cm-3) from B2H6 increased linearly with increasing flux ratio J(B2H6)/J(Si2H6) at constant T(s) and decreased exponentially with 1/T(s) at constant J(B2H6)/J(Si2H6). Secondary ion mass spectrometry analyses of modulation-doped samples, revealed sharp profiles with no detectable B segregation. Hole mobilities in uniformly doped samples were equal to bulk values.