Leakage starts in the low current region.
Figure 2 Overflow current as a function of total current at various Al compositions. The current density where leakage starts increases as Al composition increases. We need E g of about 800 meV to sufficiently suppress the leakage current. Figure 3 Overflow current as a function of total current at various p-concentrations. Figure 4 Overflow current as a function of total current at various temperatures.