Extracting carrier concentration of black c-BN single crystal by mid-infrared reflectance spectroscopy.

Cubic boron nitride (c-BN) is a synthetic ultra-wide bandgap semiconductor with attractive application prospects in electronics and optoelectronics. At present, the size of c-BN single crystals obtained by hot pressing method is generally less than 1 mm extremely unfavorable to extracting its carrier concentration through Hall effect measurement. For c-BN crystals, the longitudinal optical phonon-plasma coupling (LOPC) mode which is produced by the coupling of longitudinal optical phonons and free carriers can be observed in mid-infrared reflectance spectrum. Thus, in this work, the mid-infrared reflectance spectrum of the black c-BN crystal grown by hot pressing method is measured. Based on classical dielectric function theory, the carrier concentration of that c-BN sample is finally extracted as 7.14 × 1017 cm−3. Combining electrical measurements, its mobility is also obtained as 11.91 cm2·V-1·s-1. • The highlights of our work is as follows. • This is the first time to extract carrier concentration by fitting LOPC + mode in the mid-infrared reflectance spectrum of the black c-BN crystal, which provides a practical method to obtain the electrical properties without any contact for tiny samples. • The reliability of carrier concentration extracted from mid-infrared reflectance spectrum is confirmed through theoretical simulation. [ABSTRACT FROM AUTHOR]