Temperature dependence of step density on vicinal Pb(111)

Abstract

The temperature dependence of step density on the vicinal Pb͑111͒ surface is investigated using reflection high-energy electron diffraction. When the temperature is increased from 323 to 590 K, the average terrace width and the average string length at the step edge decrease from 85Ϯ25 to 37Ϯ16 Å and from 220Ϯ33 to 25Ϯ8 Å, respectively. Thermal step collapse on the Pb͑111͒ surface near its bulk melting temperature is not observed. Above 530Ϯ7 K, the change in the string length at the step edge with temperature becomes small, and the intensity of the ͑00͒ beam is significantly decreased. We conclude that partial step melting at the step edge occurs at the surface above 530Ϯ7 K.