Fig. 1. (Colour online) Voltage−current characteristics of light-emitting diodes with different energies of emitted quanta and power consumption (different current densities). Gray circles represent the currents where the voltage−current characteristics (VCCs) start to deviate from the exponential dependence of current on voltage.

Fig. 2. Distribution of impurity concentration in the region showing changes in the space charge of the GNL-3014PGC light-emitting diode. The gray circle indicates the position of the SCR edge in the absence of bias voltage.

Fig. 3. Volt−ampere characteristics of the GNL-3014PGC light-emitting diode. White dots refer to the VCC coordinates for a structure with one quantum well (QW), gray dots refer to the coordinates of the model VCC with three QWs, and black dots refer to the coordinates with five QWs. The calculation parameters are taken from Table 1.

Fig. 4. (Colour online) Voltage−current characteristics of the quantum wells (a), VA is total VCC; numbers indicate the VCCs corresponding to location of quantum wells on the diagram of dependence of SCR edge and its middle (b), quantum wells are marked with black lines; (c) dependence of the VCC derivative in semilogarithmic coordinates of QW 3.

Fig. 5. (Colour online) Model dependences (on a semilogarithmic scale n) of VCC derivative on forward bias voltage, obtained using the parameters listed in Table 1 for a structure with (1) three QWs and (2) five QWs. The dots indicate the values of derivative of experimental VCC of the GNL-3014PGC LED structure.

Fig. 6. (Colour online) Scheme of the formation of a built-in electric field of free charge carriers in a high-bandgap p−n homostructure: 1) diagram of the electric field in the SCR at low current densities up to 1 A/cm²; 2) electric field diagram at high current densities J > 1 A/cm²: negative values indicate built-in field of free charge carriers creating voltage U_i.

Fig. 7. (Colour online) Schematic of the formation of the built-in electric field of free charge carriers of QWs in a high-bandgap heterostructure: 1) diagram of the electric field in the SCR at low current densities up to 1 A/cm²; 2) electric field diagram at high current densities J > 1 A/cm²: negative values indicate built-in field of free charge carriers creating voltage U_i.