A novel bulk GaAs with an increased carrier lifetime of at least 10 microseconds has been produced. This novel GaAs has many uses to improve optical and electrical devices. The 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 art 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.