Igor Sokolov;Mikhail Bryushinin;Stanislav Ordin;
We report the excitation of the non-steady-state photoelectromotive force (photo-EMF) in the layered boronnitride crystal. Boron nitride crystals are characterized by an unique combination of physicochemical proper-ties that advance its wide application in various areas of science and technology such as vacuum technology,production of the microelectronic devices, x-ray lithography. The main goal of our work is to present possibil-ity to expand the non-steady-state photo-EMF technique for the new class of diamond related materials withextremely wide band gap (Eg = 5.67 eV for BN). The investigated pyrolytic BN crystal was grown using thechemical vapor deposition method. It consists of the monocrystal layers of the rhombohedral modification withthickness of 2000 A? separated by thin (～ 100 A?) layers of the hexagonal modification. The photo-EMF signal isgenerated by two coherent laser beams (λ = 532 nm) one of which is phase modulated. Both the di?usion regimeof signal excitation and the excitation in an external sinusoidal electric field are investigated. The measurementsperformed using standard di?usion regime of photo-EMF generation reveals rather low hole photoconductivityσ0 = (0.9?2.4)×10?10 ??1cm?1 at light intensities I0 = 0.22?0.86 W/cm2 and small di?usion length LD = 35nm of photoholes. We also measure the μτ-product and di?usion length using novel technique of signal genera-tion in an external ac field: μτ = 1.0 × 10?9 cm2/V, LD = 50 nm. The in?uence of the layered structure of theinvestigated BN crystal on the e?ect of the non-steady-state photo-EMF is discussed.
non-steady-state photo-EMF, boron nitride
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