| 摘要 |
An apparatus and method for creating a supply of group V vapor required for various material processing applications such as crystal growth or the mass transport process, when applied to III-V materials (e.g., GaP) comprises a stable source of group V material (e.g., a GaP wafer), a process tube, and inner tube, a three-zone furnace incorporating a cold trap zone for the group III material, and a "loose" plug for the process tube. The phosphorus vapor is generated by using a source GaP wafer placed at a higher temperature than that of the main process wafer in the mass transport process. When high phosphorous vapor concentration is desired, other solid sources such as InP or red P can be used. To minimize vapor loss to the ambient, both wafers are enclosed in a quartz tube equipped with a quartz plug. However, the source wafer generates not only phosphorus but also gallium vapor. The latter interferes with mass transport and needs to be filtered out. This is conveniently accomplished by employing a larger (longer) process tube and by further placing the source in a smaller inner tube within the main process tube. The source inner tube first directs the vapor to a cooler region, where gallium is selectively condensed out before it reaches the process wafer.
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