Model of dark current in silicon-based barrier impurity band infrared detector devices

TL;DR

The paper tackles the persistent dark current in silicon-based Blocked Impurity Band detectors by proposing a dual mechanism: at low bias, an interfacial chiral phonon-assisted spin current model that yields a quadratic field dependence $j_s \propto E^2$ and an effective Zeeman-like splitting $B_{\mathrm{eff}}=\eta \mathscr{E}$; and at higher bias, a space-constrained charge transport framework that treats trap-filling and Frenkel-field effects to generate the areal current density $J_n$. A Bogoliubov-de Gennes (BdG) formalism with a Zeeman term is used to describe spin Bogoliubov quasiparticle transport at the dopant-gradient interface. The model is calibrated against cryogenic measurements, assuming a large effective dielectric constant (e.g., $\varepsilon_{\mathrm{eff}}\approx 6\times 10^4$) and reveals how trap occupancy, tunneling, and localization govern dark current across the I–V curve. The work provides a quantitative toolkit to predict dark current and informs strategies to suppress it in silicon-based BIB detectors, potentially enabling more sensitive cryogenic infrared sensing.

Abstract

Dark current in silicon-based blocked impurity band (BIB) infrared detectors has long been a critical limitation on device performance. This work proposes a chiral-phonon-assisted spin current model at interfaces to explain the parabolic-like dark current behavior observed at low bias voltages. Concurrently, the spatially-confined charge transport theory is employed to elucidate the dark current generation mechanism across the entire operational voltage range.

Figures (4)

• Figure 1: Theoretical prediction curves of spin current density at the absorber/blocking-layer interface. Key parameters include: relaxation time of 10 ps, chemical potential at 0.15 eV, cutoff energy of 0.05 eV, transition temperature of 60 K, and chiral phonon coupling coefficient of 1e-15 $eV \cdot m \cdot V^{-1}$.
• Figure 2: Dark Current-Voltage Characteristics of Si:P BIB Devices at Different Temperatures. We generally observe a gradual variation in the curvature of the curves; the curvature remains nearly constant in the high-bias region, manifesting an insulator-to-metal transition (IMT) driven by the applied bias.
• Figure 3: Theoretical predictions of areal current density profiles derived from space-constrained charge transport theory. Calculations determine the required voltages to achieve target areal current densities at varying temperatures, utilizing the following key parameters: relative permittivity of 60000, on-site potential is 0.52eV, effective electron mass of 0.20 $m_e$, dopant energy level at -0.045eV, trap density of 1e24$m^{-3}$, and doping concentration of 1e19$m^{-3}$
• Figure 4: Typical dark current curves of a Si:P BIB device in the low-voltage regime. It can be observed that the curves are approximately parabolic in shape, with the current reaching its minimum at 6 K. This phenomenon suggests that the formation efficiency of unstable Cooper pairs at the device interface is the highest at 6 K, which is consistent with our theoretical analysis.