Deep-depleted P+– <i>v</i> –N+ HgCdTe focal plane arrays for high-operating-temperature LWIR detection

Abstract

Achieving the simultaneous optimization of quantum efficiency (QE) and dark current remains a formidable challenge for high-operating-temperature (HOT) long-wavelength infrared (LWIR) detectors. Conventional approaches to suppress Auger recombination typically aim to achieve full depletion of the absorber. However, the depletion width in practical HgCdTe devices is limited by residual background doping, often requiring absorber thinning to realize full depletion, which reduces the available absorption volume and hence quantum efficiency. In this work, we demonstrate a deep-depleted P+–v–N+ HgCdTe architecture that effectively alleviates this trade-off at the focal plane array (FPA) level. By integrating Silvaco technology computer-aided design modeling with high-precision molecular beam epitaxy, we realized a 128 × 128 FPA with a 15 μm pitch, a practical absorber thickness of ∼4.85 μm, and ultra-low v-type doping. The device exhibits a high QE of 61.48% at 77 K, together with a dark-current density approximately 85% below the empirical Rule 07 benchmark at 130 K. Arrhenius analysis over 80–130 K reveals a sub-bandgap activation energy of ∼109.5 meV, markedly lower than the Rule 07-derived value (∼154.6 meV), confirming effective suppression of intrinsic Auger recombination. In addition, the FPA maintains excellent operability (&amp;gt;99.3%) and a stable noise equivalent temperature difference (NETD &amp;lt; 20 mK) at elevated temperatures. These results demonstrate a practical route toward high-performance HOT LWIR imaging by approaching the low-dark-current regime of fully depleted devices in an array-level implementation.