HgCdTe has become the detector material of choice for many development and production electro-optical systems whose applications cover the IR spectrum from 2 to 16 micrometers , with operating temperatures ranging from 300 K to 40 K and background flux levels from 1018 to 1012 photons/cm2-sec. At the base of this success is the ongoing development and perfection of the HgCdTe material from which these detectors are fabricated. This paper examines the expressions that describe leakage currents, signal current, and capacitance for HgCdTe p+-on-n diodes to identify the critical material properties and their influence on the performance of the resulting detectors. In addition to lifetime, doping density, mobility, and composition, the compositional grading within the absorbing layer must be managed to achieve the desired performance. Equally important are parameters such as size and uniformity which must be emphasized to meet IR FPA cost targets. Caution must also be taken not to attempt to reduce IR FPA cost at the expense of material quality, because doing so would most likely have the opposite effect.