Electrical characterization of Si doped AlN films synthesized by pulsed laser deposition

The electrical properties of thin AlN films doped with Si (AlN:Si) have been investigated. The films were synthesized on Si substrates at 800 °C by pulsed laser deposition in low-pressure nitrogen ambient. The AlN:Si films exhibit non-ohmic I-V characteristics and the current through these films is controlled by space charge limited current. The C-V dependence of metal-insulator-silicon (MIS) structures with AlN:Si films exhibits an excess capacitance around zero bias voltage. This excess capacitance indicates the presence of deep acceptor levels situated at the boundaries of adjacent grains in the AlN:Si films. The Si donor density in the AlN:Si films, estimated from the 1 MHz C-V characteristics, is of the order of 10 18 cm −3 . The impedance measurements of these AlN:Si structures at different test voltage frequencies reveal that the charge transport mechanism is dominated by either thermally-activated hopping or electron tunneling from occupied to nearest unoccupied deep levels.