OPTICAL 2ND-HARMONIC GENERATION STUDY OF SI AND GE DEPOSITION ON SI(001)

Using optical second-harmonic generation, the deposition of Si and Ge on Si(001) under ultrahigh vacuum conditions has been studied, in real time. For both Si and Ge deposition at room temperature, a strong initial decrease in second-harmonic intensity has been found, showing that the technique is very sensitive to the surface electronic structure of Si(001), and that growth at this temperature destroys the long-range order. During continued deposition of Ge the second-harmonic intensity increases again, leading to a maximum at a coverage of one monolayer (ML). This is interpreted as being due to the buildup of a dipolar layer at the Si-Ge interface. For deposition at temperatures around 750 K the disorder-induced intensity decrease vanishes, whereas the formation of a dipole layer at the Si-Ge interface again induces a maximum in second-harmonic intensity at a coverage of 1 ML. © 1990, American Vacuum Society. All rights reserved.