  The Wide-Field Infrared Survey Telescope (WFIRST) will answer fundamental
questions about the evolution of dark energy over time and expand the catalog
of known exoplanets into new regions of parameter space. Using a Hubble-sized
mirror and 18 newly developed HgCdTe 4K x 4K photodiode arrays (H4RG-10),
WFIRST will measure the positions and shapes of hundreds of millions of
galaxies, the light curves of thousands of supernovae, and the microlensing
signals of over a thousand exoplanets toward the bulge of the Galaxy. These
measurements require unprecedented sensitivity and characterization of the Wide
Field Instrument (WFI), particularly its detectors. The WFIRST project
undertook an extensive detector development program to create focal plane
arrays that meet these science requirements. These prototype detectors have
been characterized and their performance demonstrated in a relevant space-like
environment (thermal vacuum, vibration, acoustic, and radiation testing),
advancing the H4RG-10's technology readiness level (TRL) to TRL-6. We present
the performance characteristics of these TRL-6 demonstration devices.
