Advanced Materials ( IF 21.95 ) Pub Date : 2018-01-03 , DOI: 10.1002/adma.201703748 Cheng Li, Ye Wu, Bingchen Deng, Yujun Xie, Qiushi Guo, Shaofan Yuan, Xiaolong Chen, Maruf Bhuiyan, Zishan Wu, Kenji Watanabe, Takashi Taniguchi, Hailiang Wang, Judy J. Cha, Michael Snure, Yingwei Fei, Fengnian Xia
Black phosphorus (BP) has recently attracted significant attention due to its exceptional physical properties. Currently, high-quality few-layer and thin-film BP are produced primarily by mechanical exfoliation, limiting their potential in future applications. Here, the synthesis of highly crystalline thin-film BP on 5 mm sapphire substrates by conversion from red to black phosphorus at 700 °C and 1.5 GPa is demonstrated. The synthesized ≈50 nm thick BP thin films are polycrystalline with a crystal domain size ranging from 40 to 70 µm long, as indicated by Raman mapping and infrared extinction spectroscopy. At room temperature, field-effect mobility of the synthesized BP thin film is found to be around 160 cm2 V−1 s−1 along armchair direction and reaches up to about 200 cm2 V−1 s−1 at around 90 K. Moreover, red phosphorus (RP) covered by exfoliated hexagonal boron nitride (hBN) before conversion shows atomically sharp hBN/BP interface and perfectly layered BP after the conversion. This demonstration represents a critical step toward the future realization of large scale, high-quality BP devices and circuits.
Synthesis of highly crystalline thin-film black phosphorus (BP) on 5 mm sapphire substrates is realized through the conversion from red phosphorus. A field-effect transistor fabricated on synthesized BP thin film shows field-effect mobility of around 160 cm2 V−1 s−1 at room temperature. Red phosphorus covered by exfoliated hexagonal boron nitride (hBN) before conversion shows atomically sharp hBN/BP interface and perfectly layered BP after the conversion.