Surface disordering without surface roughening

Abstract

The thermal disordering of indium (100) and (110) surfaces between 130 K and the melting point (${\mathit{T}}_{\mathit{m}}$=430 K) is studied by low-energy-electron diffractometry. Similar to all investigated fcc (100) surfaces, the In(100) surface does not melt below ${\mathit{T}}_{\mathit{m}}$, but contrary to the disordering behavior of all fcc (110) surfaces studied up to now, no surface roughening is observed on the In(110) surface. The disordering of the In(110) surface is attributed to the transition from large anharmonic vibrations to a quasiliquid layer via a vacancy/adatom gas of increasing density.