Data are presented on high differential efficiency quantum dot microcavity light emitting diodes. The data show that differential efficiencies >16% can be achieved by the use of quantum dots to reduce carrier diffusion in small oxide-apertured microcavities. The measured efficiencies are sensitive to both microcavity tuning of the resonance peak to the quantum dot light emitters, and nonradiative recombination effects brought on by temperature, bias current, and edge effects. The peak efficiencies are obtained at a resonance temperature of similar to160 K. (C) 2002 American Institute of Physics.