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

¹ Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria
² Technical University – Sofia, 8 Kliment Ochridski blvd., 1000 Sofia, Bulgaria
³ National Institute for Lasers, Plasma, and Radiation Physics, PO Box MG-54, 77125 Magurele, Ilfov, Romania

^a e-mail: szekeres@issp.bas.bg

Received: 20 April 2014
Revised: 24 October 2014
Accepted: 23 March 2014
Published online: 21 April 2015

Abstract

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 10¹⁸ 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.