Growth and pre-cooling doping of semiconducting C-doped hBN as a sensitive thermistor

Abstract

This letter describes the growth of hexagonal boron nitride (hBN) on plateau and terrace regions of nickel foil by tuning the V/III ratio of NH3 and B2H6, followed by pre-cooling carbon doping with CH4. The V/III ratio = 120 with a growth duration of 30 min is good to grow ∼ 14 nm-thick hBN for the application requiring it as an insulator. Pre-cooling doping by CH4 is possible because crystallizing BN prevents carbon from diffusing into bulk nickel and allows the substitution of nitrogen atoms. The C-doped hBN is having a lowered bandgap of 5.79/5.47 eV, sub-bandgap of 2.86 eV, narrowed Raman E2g peak on plateau and terrace regions, a slight decrease in nitrogen atomic%, and reduced thickness. These convert hBN from an insulator into a semiconductor. The C-doped hBN is a very sensitive thermistor with a temperature coefficient of resistance up to –0.037 K−1.