A system and method for producing bulk GaAs with an increased carrier lifetime of at least 10 microseconds is provided. The system and method of producing the GaAs crystal involves using a technique called low pressure hydride vapor phase epitaxy (LP-HVPE). In this technique, a gas containing Ga (typically GaCl) is reacted with a gas containing As (typically AsH3) at the surface of a GaAs substrate. When grown under the proper conditions, the epitaxial, vapor grown GaAs crystal has ultra-long free carrier lifetimes of at least one order of magnitude greater than that of the previous lifetime of 1 microsecond. This very long free carrier lifetime GaAs will be particularly useful as a semiconductor radiation detector material and is also expected to be useful for many other applications than include medical imaging, solar cells, diode lasers, and optical limiters and other applications.