Law 19: The ultimate photodiode performance metric

Abstract

In 2007, Teledyne presented and subsequently published an empirically derived formula, known as “Rule 07”, for the dark current performance of Mercury Cadmium Telluride (HgCdTe) P-on-n diodes. The Rule 07 metric has become widely popular within the infrared community, not only as a basis for predicting HgCdTe detector and system performance, but as the “number to beat” for other technologies, notably III-V nBn and strained-layer superlattice (SLS) devices. For materials that have sufficiently long recombination lifetimes, HgCdTe being one of the few such widely used materials, internal currents within the detector can be suppressed and the detector becomes limited by the background radiation from the surrounding environment. These currents can be orders of magnitude below Rule 07 and even further orders of magnitude below the Auger-limit. The ability to suppress Auger currents and operate at the radiative limit allows for significantly higher operating temperature and provides several significant advantages, including:  Reduced size, weight, power, cost, and improved reliability associated with reduced cooler requirements  Lower dark current when operating at conventional temperatures, permitting improved sensitivity from lower shot noise and longer achievable integration times Because background radiatively-limited performance is both fundamental and physics-driven, in 2019 we proposed replacing Rule 07 with “Law 19” and provided a comparison of this fundamental limit with Rule 07. In this paper, we review the theoretical performance of Teledyne’s fully-depleted HgCdTe P-υ-N detectors and provide performance data on dark current, dynamic impedance and quantum efficiency (QE) for mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) detectors both at high operating temperatures (up to 300K) and as a function of temperature