GaN ultraviolet avalanche photodiodes with optical gain greater than 1000 grown on GaN substrates by metal-organic chemical vapor deposition
We report the performance of GaN p-i-n ultraviolet avalanche photodiodes grown on bulk GaN substrates by metal-organic chemical vapor deposition. The low dislocation density in the devices enables low reverse-bias dark currents prior to avalanche breakdown for similar to 30 mu m diameter mesa photodetectors. The photoresponse is relatively independent of the bias voltage prior to the onset of avalanche gain which occurs at an electric field of similar to 2.8 MV/cm. The magnitude of the reverse-bias breakdown voltage shows a positive temperature coefficient of similar to 0.05 V/K, confirming that the avalanche breakdown mechanism dominates. With ultraviolet illumination at lambda similar to 360 nm, devices with mesa diameters of similar to 50 mu m achieve stable maximum optical gains greater than 1000. To the best of our knowledge, this is the highest optical gain achieved for GaN-based avalanche photodiodes and the largest area III-N avalance photodetectors yet reported. (c) 2006 American Institute of Physics.
Limb, J. B., Yoo, D., Ryou, J. H., Lee, W., Shen, S. C., Dupuis, R. D., ... Evans, K. (2006). GaN ultraviolet avalanche photodiodes with optical gain greater than 1000 grown on GaN substrates by metal-organic chemical vapor deposition. Applied Physics Letters, 89(1). DOI: 10.1063/1.2219390