EFFECTS OF TRACE SURFACE OXIDATION IN LOW-TEMPERATURE EPITAXY-GROWN FROM DICHLOROSILANE

The hydrogen carrier gas in an atmospheric pressure epitaxial growth r eactor is found to suppress the oxidation of a Si surface intentionall y exposed to trace oxygen before epitaxial growth. After an initial de lay the oxidation proceeds rapidly to form nanometer size oxide island s at surface coverages in the range of 0.001 to 1 monolayers. A small fraction of the oxide islands nucleate visible pyramidal-shaped defect s in the subsequently grown epitaxial layer which enables the interfac ial oxidation process to be easily studied. Replacement of the hydroge n ambience with argon leads to more than an order of magnitude increas e in initial oxidation rate and a many order of magnitude increase in the density of pyramidal defects for the same trace oxygen exposure. T he pyramid density is proportional to the square of the interfacial ox ygen density over a wide range of surface oxygen density, 5 x 10(11) c m(-2) to 10(15) cm(-2), and for sample prepared over a wide range of e xperimental conditions.