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The study of dopant segregation behavior during the growth of gaas in microgravity (Document No: 19950007801)
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Matthiesen, David H. Majewski, J. A. |
| Copyright Year | 1994 |
| Description | An investigation into the segregation behavior of selenium doped gallium arsenide during directional solidification in the microgravity environment was conducted using the Crystal Growth Furnace (CGF) aboard the first United States Microgravity Laboratory (USML-1). The two crystals grown were 1.5 cm in diameter and 16.5 cm in length with an initial melt length of 14 cm. Two translation periods were executed, the first at 2.5 microns/s and after a specified time, which was different between the two experiments, the translation rate was doubled to 5.0 microns/s. The translation was then stopped and the remaining sample melt was solidified using a gradient freeze technique in the first sample and a rapid solidification in the second experiment. Measurement of the selenium dopant distribution, using quantitative infrared transmission imaging, indicates that the first sample initially achieved diffusion controlled growth as desired. However, after about 1 cm of growth, the segregation behavior was driven from a diffusion controlled growth regime to a complete mixing regime. Measurements in the second flight sample indicated that the growth was always in a complete mixing regime. In both experiments, voids in the center line of the crystal, indicative of bubble entrapment, were found to correlate with the position in the crystal when the translation rates were doubled. |
| File Size | 1656505 |
| Page Count | 40 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19950007801 |
| Archival Resource Key | ark:/13960/t9285839j |
| Language | English |
| Publisher Date | 1994-05-01 |
| Access Restriction | Open |
| Subject Keyword | Materials Processing Crystal Growth Gallium Arsenides Directional Solidification Crystals Crystals Rapid Quenching Metallurgy Infrared Imagery Freezing Solidification Voids Entrapment Bubbles Doped Crystals Furnaces Melts Crystal Growth Thermal Conductivity Selenium Diffusion Microgravity Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
