(Invited) Solution Processing and Device Integration of Two-Dimensional Black Phosphorus

Two-dimensional black phosphorus (2D BP) has emerged as a promising candidate for next-generation electronics and optoelectronics. As is common for new materials, much of the early work on 2D BP has focused on measuring and optimizing intrinsic properties on small samples under idealized conditions. However, real-world devices and systems inevitably require large-area samples that are integrated with dielectrics, contacts, and other semiconductors at standard temperature and pressure conditions. These requirements are particularly challenging to realize for 2D BP since its properties are highly sensitive to surface chemistry, defects, and the surrounding environment. This talk will thus explore methods for improving the uniformity of solution-based 2D BP with an eye toward realizing scalable processing of large-area thin-films. Specifically, methods for exfoliating black phosphorus in anhydrous organic solvents will be discussed such that the resulting 2D BP flakes show field-effect transistor mobilities and on/off ratios that are comparable to micromechanically exfoliated flakes [1]. In addition to solution processing, this talk will also report on the integration of 2D BP with dielectrics and other materials. In particular, atomic layer deposition of alumina dielectrics on 2D BP suppresses ambient degradation, thereby preserving electronic properties in field-effect transistors at atmospheric pressure conditions [2].

[1] J. Kang, J. D. Wood, S. A. Wells, J.-H. Lee, X. Liu, K.-S. Chen, and M. C. Hersam, “Solvent exfoliation of electronic-grade, two-dimensional black phosphorus,” ACS Nano, DOI: 10.1021/acsnano.5b01143 (2015).

[2] J. D. Wood, S. A. Wells, D. Jariwala, K.-S. Chen, E. Cho, V. K. Sangwan, X. Liu, L. J. Lauhon, T. J. Marks, and M. C. Hersam, “Effective passivation of exfoliated black phosphorus transistors against ambient degradation,” Nano Lett., 14, 6964 (2014).