Si(001)2×1 gas-source molecular-beam epitaxy from Si2H6: Growth kinetics and boron doping

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Abstract
The growth rates RSi of Si films deposited on Si(001)2×1 from Si2H6 by gas‐source molecular‐beam epitaxy were determined as a function of temperature Ts (500–950 °C) and impingement flux JSi2H6 (0.3–7.7×1016 cm−2 s−1). RSi (Ts,JSi2H6) 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 (CB=5×1016–3×1019 cm−3) from B2H6 increased linearly with increasing flux ratio JB2H6/JSi2H6 at constant Ts and decreased exponentially with 1/Ts at constant JB2H6/JSi2H6. 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.