Photocurrent Generation Mechanisms in Molybdenum‐Contacted Semiconducting Black Phosphorus and Contributions from the Photobolometric Effect

Abstract

An analysis of the optoelectronic properties and photocurrent generation mechanisms in 2D multilayer crystallites of black phosphorus (BP) is conducted from 350 K down to cryogenic temperatures T of ≈6 K using a broad‐band white light source, and the results are compared to another semiconducting van der Waals solid, MoS2. Both the BP and MoS2 devices are contacted with Mo at the bottom as the electrode metal. The Mo–BP interface yields a low Schottky barrier ≈ −28.3 meV and a high photoresponsivity R of ≈2.43 × 105 A W−1 at a source‐drain bias voltage of ≈0.5 V (300 K, and incident optical power ≈3.16 μW cm−2). This article is the first to highlight the empirical use of Mo as a contact metal with BP. The high R is attributed to the low at the interfaces, in conjunction with the large effective area of a bottom contact architecture that increases the collection of photoexcited carriers and reduces thermal dissipation into the substrate from the largely suspended 2D nanodiaphragm. The results show the promise of BP to potentially advance thermoelectric and optoelectronic devices stemming from this monoelemental, direct bandgap 2D van der Waals solid.