Fig. 1. (a) Schematic diagram of SC-EL inspection system. (b) Picture of the SC-EL inspection system. (c) Schematic diagram showing the carriers transport and the generation of radiative recombination. (d) Schematic diagram showing the accumulation of carriers and the depletion region. (e) Schematic diagram showing the pre-accumulated carriers dissipating through the circuit. (f) Schematic diagram showing the reverse accumulation of carriers.

Fig. 2. Distribution of electron and hole concentrations in one voltage cycle. (a) At 0 μs, 1.25 μs, 2.5 μs, respectively. (b) At 3.75 μs, 5 μs, respectively. (c) At 6.25 μs, 7.5 μs, 8.75 μs, respectively.

Fig. 3. Equivalent electrical circuit of the SC-EL system.

Fig. 4. (a) Typical PWL obtained by using the SC-EL inspection. (b) Typical measured AC current by using the SC-EL inspection. (c) Microscopy image of LED epitaxial wafer surface after conventional EL inspection. (d) Microscopy image of LED epitaxial wafer surface after SC-EL inspection.

Fig. 5. (a) PWL mapping and physical diagram of SC-EL inspection. (b) PWL mapping and physical diagram of PL inspection. (c) PWL mapping and physical diagram of conventional EL inspection. (d) PWL error of SC-EL inspection. (e) PWL error of PL inspection.

Fig. 6. (a) Luminescence of MQW inside LED epitaxial wafer during electroluminescence. (b) Luminescence of MQW inside LED epitaxial wafer during photoluminescence.

Fig. 7. (a) Waveform of the applied AC voltage (top panel) for SC-EL inspection and the measured currents of different LED epitaxial wafer regions. (b) DC I-V curves of the corresponding LED epitaxial wafer regions.

Fig. 8. Comparison of existing inspection methods.

Table 1. Comparison of Existing Inspection Methods^a