Indium incorporation during the growth of (100)Si by molecular beam epitaxy: Surface segregation and reconstruction

摘要

The In incorporation probability sgr;Inin (100) Si grown by molecular beam epitaxy was found, using secondary ion mass spectrometry (SIMS), to decrease from essentially unity at film growth temperaturesTsof sim;500thinsp;deg;C to 10minus;4at 840thinsp;deg;C. SIMS depth profiles of both uniformly doped and modulationhyphen;doped samples showed evidence of strong surface segregation with the amount of profile broadening directly related to sgr;In(Ts). A combination ofinsituelectron diffraction and Auger electron spectroscopy was used to show that the surface segregation rate was sufficient over a wide range inTsand In to Si flux ratios to cause the initial (2times;1)hyphen;(100) Si surface reconstruction to transform to (3times;4) due to the formation of an ordered In surface layer. The In surface coverage in the (3times;4) state was sim;0.05ndash;0.1 monolayer even though the bulk In concentration was le;2times;1017cm3. The (2times;1) to (3times;4) surface phase transition was reversible by either terminating film growth and reevaporating the excess surface In or terminating the In flux while continuing Si film growth.