Rapid growth of a 24 mm2 scale hexagonal boron nitride crystal in Ni–Cr solution

Abstract

A high quality and large size hexagonal boron nitride (hBN) crystal was successfully grown in Ni–Cr solution at 1550 °C. The total growth time was reduced from 68.88 hours to 49.17 hours using a specially designed cooling protocol. The thickness of the grown hBN film was found to be 300 μm, and an area of a mechanically exfoliated hBN film of up to 24 mm² was achieved. The narrow X-ray diffraction peak of the (002)-plane hBN and the Raman E_2g vibration peak indicated a high crystalline quality of hBN grown in this study. Furthermore, a metal–semiconductor–metal type photodetector was prepared, the dark current density and photocurrent density with a bias voltage of 10 V of which were 1.5 and 500 pA cm⁻¹, respectively. A high signal-to-noise ratio of 2 orders of magnitude was achieved, further proving the high crystalline quality of the hBN crystal grown in this study.