从电传输性质定量测定体 PdSe2 的矛盾带隙值,Advanced Functional Materials

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从电传输性质定量测定体 PdSe2 的矛盾带隙值
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2021-11-17 , DOI: 10.1002/adfm.202108061
Wataru Nishiyama ₁ , Tomonori Nishimura ₁ , Keiji Ueno ₂ , Takashi Taniguchi ₃ , Kenji Watanabe ₄ , Kosuke Nagashio ₁

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据报道， 2D PdSe ₂是一种第 10 族贵金属二硫化物，具有很强的厚度依赖性带隙能量，范围从 ≈1.6 eV（单层）到 ≈0.05 eV（体），并且在远红外中对大块样品具有高光响应性波长范围为 10.6 μm。然而，通过光吸收测量，对于块状 PdSe ₂的中间带隙约为 0.5 eV 的报道相互矛盾。在这项研究中，进行了详细的电传输测量以解决这一矛盾。窄间隙半导体和中等间隙半导体之间的主要区别在于耗尽层对传输特性的贡献。霍尔测量显示本征p型载流子密度约为 1.9 × 10 ¹⁸ cm ^-3在 300 K 和耗尽层对块状 PdSe ₂传输特性的贡献，表明中间带隙。此外，最大耗尽宽度 ( W _Dm ) 由双栅晶体管中的顶栅和背栅耦合决定，约为 17-18 nm。根据W _Dm – 受体密度图，定量估计块状 PdSe _{2的带隙约为 0.3 eV。}虽然从远红外材料的角度来看，这不是一个理想的结果，但它有助于我们正确理解 PdSe ₂的光响应机制。

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Quantitative Determination of Contradictory Bandgap Values of Bulk PdSe2 from Electrical Transport Properties

2D PdSe₂, a Group 10 noble metal dichalcogenide, has been reported to have a strong thickness-dependent bandgap energy, ranging from ≈1.6 eV (monolayer) to ≈0.05 eV (bulk) and a high photoresponsivity for bulk samples in the far infrared wavelength range of 10.6 μm. However, a middle bandgap of ≈0.5 eV has been contradictorily reported for bulk PdSe₂ via optical absorption measurements. In this study, detailed electrical transport measurements are conducted to solve this contradiction. The key difference between narrow gap and middle gap semiconductors is the contribution of a depletion layer to the transfer characteristics. Hall measurements reveal intrinsic p-type carrier densities of ≈1.9 × 10¹⁸ cm⁻³ at 300 K and the contribution of the depletion layer to the transfer characteristics for bulk PdSe₂, suggesting a middle bandgap. Moreover, the maximum depletion width (W_Dm) is determined from top- and back-gate coupling in dual gate transistors to be ≈17–18 nm. Based on the W_Dm – acceptor density diagram, the bandgap of bulk PdSe₂ is quantitatively estimated to be ≈0.3 eV. Although this is not a desirable result from the viewpoint of far infrared material, it helps us to correctly understand the mechanism for the photoresponse of PdSe₂.

更新日期：2021-11-17

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