Sharp profiles with high and low doping levels in silicon grown by molecular beam epitaxy

摘要

We find that heavy adsorbed dopant layers, up to several tens of equivalent monolayers, can be made to produce heavily dopedn(Sb) andp(Ga) layers in molecular beam epitaxy grown silicon. By preadjusting the adlayer concentration to the required value while temporarily arresting silicon growth, arbitrarily sharp profiles of any sequence of dopant type with very high or low levels can be grown. Examples are given ofp+ip+andn++p+pp+structures grown with transition thicknessLquest;300 Aring;, and with controlled layer thicknesses of sim;1000 Aring;. Such structures, difficult to achieve otherwise, should be ideal for fabrication of highhyphen;frequency millimeter wave devices.