Electrical characterization of GaN based blue light emitting diodes

Blue light emitting diodes (LEDs), based on an AlGaN/GaN/AlGaN double heterojunction structure, have been electrically characterized. These diodes are highly non-ideal with several approximately linear regimes in the semi-logarithmic plots of the forward characteristics. Calculated values of the ideality factor range from 3.0-7.0, indicating that the recombination process in these diodes cannot be conveniently described by the Shockley-Read-Hall statistics. Logarithmic plots of the forward characteristics indicate a space-charge-limited-current (SCLC) conduction through the active region of the diodes. Observed changes in the slope of these logarithmic plots are representative of a high density of "deep-level states" in the active region of the diodes. An analysis of these characteristics yielded an approximate density of deep-level states of 2×10¹⁷/cm³. These states are most likely located close to the valence band edge, in the compensated active region of the diodes.