Electron emission from CVD diamond p-i-n junctions with negative electron affinity during room temperature operation

We successfully observed electron emission from hydrogenated diamond p-i-n junction diodes with negative electron affinity during room temperature operation. The emissions started when the applied bias voltage produced flat-band conditions, where the capacitance-voltage characteristics showed carrier injection in the i-layer. In this low current injection region, the electron emission efficiency (eta) of the p-i-n junction diodes (p is top layer) was about 5 x 10(-5), while that of the n-i-p diodes (n is top layer) was about 10(-8). With increasing diode current, both diodes showed an increase in eta and a nonlinear increase in emission current. In the high current injection region with high diode current of 5-50 mA, both diodes had an emission current of almost 10 mu A, where eta of a p-i-n junction diode was 0.18%, while that of a n-i-p junction diode was 0.02%. Note that eta, which corresponds to the electron emission mechanism, depended on the diode current level. (C) 2011 Elsevier B.V. All rights reserved.