Amorphization of hard crystalline materials by electrosprayed nanodroplet impact
Abstract
A beam of electrosprayed nanodroplets impacting on single-crystal silicon amorphizes a thin surface layer of a thickness comparable to the diameter of the drops. The phase transition occurs at projectile velocities exceeding a threshold, and is caused by the quenching of material melted by the impacts. This article demonstrates that the amorphization of silicon is a general phenomenon, as nanodroplets impacting at sufficient velocity also amorphize other covalently bonded crystals. In particular, we bombard single-crystal wafers of Si, Ge, GaAs, GaP, InAs, and SiC in a range of projectile velocities, and characterize the samples via electron backscatter diffraction and transmission electron microscopy to determine the aggregation state under the surface. InAs requires the lowest projectile velocity to develop an amorphous layer, followed by Ge, Si, GaAs, and GaP. SiC is the only semiconductor that remains fully crystalline, likely due to the relatively low velocities of the beamlets used in this study. The resiliency of each crystal to amorphization correlates well with the specific energy needed to melt it except for Ge, which requires projectile velocities higher than expected.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 07, 2014
- Source ID
- 10.1063/1.4901287
Entities
People
- Anna Torrents
- Jian-guo Zheng
- Manuel Gamero-Castaño
- Rafael Borrajo-pelaez
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- University of California