Atomic-layer adsorption of P on Si 100/ and Ge 100/ by PH3 using an ultraclean low-pressure chemical vapor deposition

Atomic-layer adsorption of P on Si 100. and Ge 100. at 200–7508C by PH3 was investigated using an ultraclean low-pressure chemical vapor deposition CVD.system. At 3008C, the PH3 adsorption was suppressed on the H-terminated Si surface, but PH3 was adsorbed dissociatively on the H-free Si surface with saturation tendency to subatomic layer. At 450–7508C, the P atom concentration on the Si surface tended to saturate to about two or three atomic layers by exposing PH3with little influence of the carrier gas H2or He.. When the P-adsorbed Si was kept in Ar and in H2at 6508C after PH3 exposure, the P atom concentration decreased to about one atomic layer by thermal desorption and also by reduction due to hydrogen. On the Ge surface, PH3 adsorption was suppressed by H-termination at 2008C, P atom concentration saturated to the single atomic layer at 300–4508C. Furthermore, P desorption from the Ge surface at 4508C occurred much faster than that from the Si surface at 6508C, while P bonded to Ge was stable at 3008C. q2000 Elsevier Science B.V. All rights reserved.