Photo-, cathode-, and electroluminescence from erbium and oxygen co-implanted GaN

Efficient Er-related photo-, cathode-, and electroluminescence at 1539 nm was detected from Er and O co-implanted n-type GaN on sapphire substrates. Several combinations of Er and O implants and postimplant annealing conditions were studied. The Er doses were in the range (0.01-5) x 10(15) ions/cm(2) and O doses (0.1-1)x 10(16) ions/cm(2). GaN films implanted with 2 x 10(15) Er2+/cm(2) at 350 keV and co implanted with 10(16) O+/cm(2) at 80 keV yielded the strongest photoluminescence intensity at 1539 nm. The annealing condition yielding the strongest Er-related photoluminescence intensity was a single anneal at 800 degrees C (45 min) or at 900 degrees C (30 min) in flowing NH3. The optimum O:Er ratio was found to be between 5:1 and 10:1. Go-implanting the GaN:Er films with F was also found to optically activate the Er, with slightly (20%) less photoluminescence intensity at 1539 nm compared to equivalent GaN:Er,O films. The Er-related luminescence lifetime at 1539 nm was found to depend on the excitation mechanism. Luminescence lifetimes as long as 2.95 +/- 0.15 ms were measured at 77 K under direct excitation with an InGaAs laser diode at 983 nm, At room temperature the luminescence lifetimes were 2.35 +/- 0.12, 2.15 +/- 0.11, and 1.74 +/- 0.08 ms using below-band-gap excitation, above-band-gap excitation, and impact excitation (reverse biased light emitting diode), respectively. The cross sections for Er in GaN were estimated to be 4.8 x 10(-21) cm(2) for direct optical excitation at 983 nm and 4.8 x 10(-16) cm(2) for impact excitation. The cross-section values are believed to be within a factor of 2-4. (C) American Institute of Physics.