Time-Resolved Reflectivity Measurement of Extrinsic Silicon during Pulsed Laser Irradiation.
Abstract
Time-resolved reflectivity (TRR) of crystalline silicon has been measured with nanosecond resolution during and immediately after pulsed neodymium glass laser irradiation (1.06 micrometers, full width at half maximum pulse duration of 20 ns) over a range of pulsed laser energy densities. The TRR information was used to determine energy density thresholds for melting and damaging the polished surface of extrinsic silicon wafers. Reflectivity initially increased under laser irradiation and then returned to its original value for energy densities between 0.46 J/sq cm and 1.05 sq cm. For energy densities greater than 1.05 J/sq cm, the final value of reflectivity was less than the original value due to permanent target damage. The damage threshold was substantiated with optical photomicrographs. A qualitative examination was undertaken to determine the change in specular and diffuse reflection from the target surface as a function of the degree of laser-induced damage.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1984
- Accession Number
- ADA150350
Entities
People
- E. L. Chenoweth
- G. D. Johnson
Organizations
- Naval Postgraduate School