Electron Field Emission from Aluminum Nitride

AlN has been identified as a candidate material for cold cathode field emitters due to its purported negative electron affinity (NEA) surface. Recent studies by our group on AlN(0001) using angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) and scanning electron microscopy (SEM) have indicated that AlN(0001) is a positive electron affinity surface. We have also investigated electron field emission behavior of AlN and pure Al films grown on Si. AlN and Al films were grown by molecular beam epitaxy (MBE) and transported via an ultra-high vacuum (UHV) integrated processing system (IPS) to an electron emission measurement system (EEMS). The reference Al film on Si showed characteristic Fowler-Nordheim behavior with a turn-on field of 120V/μm (defined at 10μA-cm-2) and ∼100μA-cm-2 emission at 140V/μm. The AlN film also showed Fowler-Nordheim behavior with a turn-on field of 60V/μm and ∼10mA-cm-2 at 100V/μm. Air exposure of the AlN film caused a shift in turn-on to 90V/μm and ∼0.1mA-cm-2 at 100V/μm. The I-V behavior of the AlN film is consistent with the ARUPS results on a different AlN sample - both indicating a positive electron affinity AlN surface.