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

摘要

An analysis of the optoelectronic properties and photocurrent generationmechanisms in 2D multilayer crystallites of black phosphorus (BP) is conductedfrom 350 K down to cryogenic temperatures T of ≈6 K using a broad-band whitelight source, and the results are compared to another semiconducting van derWaals solid, MoS_2. Both the BP and MoS_2 devices are contacted with Mo atthe bottom as the electrode metal. The Mo-BP interface yields a low Schottkybarrier Φ_(SB)≈28.3 meV and a high photoresponsivity R of ≈2.43 × 10~5AW~(-1)at a source-drain bias voltage of ≈0.5 V (300 K, and incident optical power≈3.16 μWcm~(-2)). This article is the first to highlight the empirical use of Mo as acontact metal with BP. The high R is attributed to the low Φ_(SB) at the interfaces, inconjunction with the large effective area of a bottom contact architecture thatincreases the collection of photoexcited carriers and reduces thermal dissipationinto the substrate from the largely suspended 2D nanodiaphragm. The resultsshow the promise of BP to potentially advance thermoelectric and optoelectronicdevices stemming from this monoelemental, direct bandgap 2D van der Waalssolid.