Observation of blistering and amorphization on germanium surface after 450 keV Ar+ion bombardment

Abstract
Blistering on the surface of germanium is observed, for the first time, after 450 keV Ar+ ion bombardment. The number of blisters saturates at about 5 × 105/cm2. Further bombardment induces pores on the surface, which are considered to be associated with injected gas-release. These pores erode the surface, and, eventually, get rid of the previously formed blisters. These observations are qualitatively explained by amorphization on the germanium surface. The amorphization make the range of energetic ions shorter, and, at the same time, the injected ions more mobile due to the volume expansion. The observed depths of blisters are more than 1 μm, namely, more than three times larger than the projected range of ions due to Schi⊘tt. Amorphization and its recrystallization at room temperature on further bombardment are observed by electron diffractometry.