Band-edge electroluminescence from N+-implanted bulk ZnO

N+ ion implantation at moderate doses (10(13)-10(14) cm(-2)) into nominally undoped (n similar to 10(17) cm(-3)) bulk single-crystal ZnO substrates followed by annealing in the range 600-950 degrees C was used to fabricate diodes that show visible luminescence at 300 K and band-edge electroluminescence at 120 K (similar to 390 nm) under forward bias conditions. The current-voltage behavior of the diodes are characteristic of metal-insulator-semiconductor devices and suggest the implantation creates a more resistive region in the n-ZnO in which holes are created by impact ionization during biasing, similar to the case of electroluminescence in ZnO varistors. The series resistance is only 25 Omega due to the use of the conducting ZnO substrate. (c) 2006 American Institute of Physics.