Energetic states in the boron nitride band gap

Energetic and kinetic characteristics of charge carrier trapping and recombination centres in graphite-like Pyrolytic Boron Nitride (PBN) produced by gas-phase deposition are discussed. Local levels in X-ray excited PBN are studied using thermally activated spectroscopy of luminescence and conduction, and their positions in the band gap are determined from the temperature dependences of the diffusive current. Acceptor and donor level models for different PBN are developed. Their influence on conduction and on luminescence is determined. A scheme for electron-hole and hole-electron transitions by luminescence is suggested. The influence of carbon on the nature of the defects creating local levels is discussed. Comparatively shallow donor (1.3 and 1.1 eV) and acceptor (1.2 and 1.15 eV) levels are caused by the defects: nitrogen vacancies (V_N), boron vacancies (V_B), and carbon stabilized vacancies, respectively. Deep levels may be created by intercalation carbon compounds.