Ultra-Hard (41 GPa) Isotopic Pure ¹⁰BP Semiconductor Microwires for Flexible Photodetection and Pressure Sensing.

Abstract

An urgent demand for electronic and optoelectronic devices able to work in extreme environments promotes a series of research studies on semiconductor materials. Cubic boron phosphide (BP) as a semiconductor material with excellent characteristics shows great application potential. However, since the synthesis conditions required are difficult to achieve and the growth mechanism of BP is still unclear, there are few reports on the basic properties of BP and pure isotope BP, resulting in a narrow understanding of their special physical properties. Here, we successfully obtained highly pure isotopic ¹⁰BP crystals by a vapor-liquid-solid (VLS) method unconventionally designed, which successfully overcomes the thermodynamic conflict between the high melting point of the boron element and low sublimation temperature of the phosphorus element. The ¹⁰BP achieved owns an aspect ratio as high as 10⁴ and a hardness up to 41 GPa. Besides, as an indirect bandgap semiconductor, it has ultrawide red emission spectra, a p-type conductivity with extremely low resistivity, and excellent photoelectronic and piezoelectric characteristics. Furthermore, compared with other superhard semiconductors like cubic BN and diamond, ¹⁰BP has an obvious advantage of lower growth temperature (1200 °C). All these characteristics confirm the prospects owned by ¹⁰BP in its applications to the field of high-conductivity, optoelectronic, strain-sensing, and superhard semiconductors.