Black phosphorus (BP) has recently emerged as a promising narrow band gaplayered semiconductor with optoelectronic properties that bridge the gapbetween semi-metallic graphene and wide band gap transition metaldichalcogenides such as MoS2. To date, BP field-effect transistors haveutilized a lateral geometry with in-plane transport dominating devicecharacteristics. In contrast, we present here a vertical field-effecttransistor geometry based on a graphene/BP van der Waals heterostructure. Theresulting device characteristics include high on-state current densities (>1600 A/cm2) and current on/off ratios exceeding 800 at low temperature. Twodistinct charge transport mechanisms are identified, which are dominant fordifferent regimes of temperature and gate voltage. In particular, the Schottkybarrier between graphene and BP determines charge transport at hightemperatures and positive gate voltages, whereas tunneling dominates at lowtemperatures and negative gate voltages. These results elucidate out-of-planeelectronic transport in BP, and thus have implications for the design andoperation of BP-based van der Waals heterostructures.
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机译：黑磷（BP）近来已成为具有光电子学性能的有希望的窄带隙层状半导体，该半导体具有弥合半金属石墨烯与宽带隙过渡金属二卤化物（如MoS2）之间的间隙的能力。迄今为止，BP场效应晶体管已利用具有面内传输主导器件特征的横向几何形状。相反，我们在此介绍基于石墨烯/ BP Van der Waals异质结构的垂直场效应晶体管几何形状。器件的特性包括高导通电流密度（> 1600 A / cm2）和低温下的电流开/关比超过800。确定了两种不同的电荷传输机制，它们是温度和栅极电压的不同状态的主导。特别是，石墨烯和BP之间的肖特基势垒决定了高温和正栅极电压下的电荷传输，而隧穿在低温和负栅极电压下占主导地位。这些结果阐明了BP中的平面外电子传输，因此对基于BP的范德华异质结构的设计和操作具有影响。
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