Charge transport generation-recombination mechanism in MoS2 based Schottky diodes

Abstract

The introduction of MoS₂, a two-dimensional transition metal dichalcogenide (TMD), provides unique electronic properties, including a tunable bandgap and high carrier mobility which makes it a promising material for optoelectronic applications. Here, the carrier transport in a Schottky Diode with a sandwiched structure of Pt electrode, n-type MoS₂ and Cr electrode has been investigated. Understanding the charge transport dynamics at Pt/MoS₂ junction of the diode is crucial for optimizing their performance in photodetectors and solar cell applications. The current–voltage (I-V) characteristics of the diode are quantitatively interpreted using the Sah–Noyce–Shockley theory, which describes generation-recombination mechanisms in the space-charge region for a fully depleted layer. The charge transport mechanisms in the Pt/MoS₂/Cr Schottky diode are dominated by recombination processes within the depletion width. The ideality factor remains nearly constant at n = 1.15 across different voltage ranges, challenging conventional thermionic emission models. The Schottky barrier height at the Pt/MoS₂ interface exhibit a built-in voltage dependence. The I–V characteristics are significantly influenced by the optimum bulk properties: mid-gap defect level (Eₜ = 0.75 eV), barrier height (φ₀=0.55 eV), and carrier lifetimes (τₙ = τₚ = 1.5 × 10⁻¹⁰ s). Increased ideality factor (n = 1.2–1.8) reflects an impeded charge transport or increased recombination due to defects and leakage current.