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Gaussian impurity bands in GaN responsible for intracenter optical absorption and photoluminescence, give rise to defect-assisted carrier tunneling (hopping) through the barriers in the pn nanostructures with InGaN/GaN quantum wells (QWs). The tunneling injection of majority cariers into the QW results in the current humps and in rapid increase in the radiative recombination efficiency at low enough forward bias. As the bias increases, the carrier confinement in the QW weakens, leading to tunneling injection of minority cariers into the barriers, which results in the emission efficiency saturation and droop.

No abstract

It is shown that the emission efficiency and the 1/f noise level in light emitting diodes with InGaN/GaN quantum wells correlate with how the differential resistance of a diode varies with increasing current. Analysis of the results shows that hopping transport via defect states across the n type part of the space charge region results in limitation of the current by the tunneling resistance at intermediate currents and shunting of the n type barrier at high currents. The increase in the average number of tunneling electrons suppresses the 1/f current noise at intermediate currents. The strong growth in the density of current noise at high currents, S J ∝ J 3 , is attributed to a decrease in the average number of tunneling electrons as the n type barrier decreases in height and width with increasing forward bias. The tunneling recombination leakage cur rent along extended defects grows faster than the tunneling injection current, which leads to emission effi ciency droop.