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We investigate the reverse leakage characteristics of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) grown on Si (111) substrate by metal-organic chemical vapor deposition. The reverse leakage characteristics of InGaN/GaN LED on silicon are measured as low as ~10 nA at -5 V and -10 μA at -15 V. Temperature-dependent current-voltage (I-V) measurements of LED devices reveal that the reverse leakage current mechanism is mainly attributed to the field-enhanced thermionic emission, also known as Poole-Frenkel emission, of carriers from deep centers within the space charge region up to ~ -18 V. The analysis of T-I -V curve yields the calculation of the coefficient of the Poole-Frenkel effect (1.12 × 10-4 eV·V-1/2·cm1/2) and activation energies of carriers (~214 meV at -5 V). With further increase of reverse bias, up to -40 V, LED devices exhibit the onset of space-charge-limited leakage current mechanism without any local breakdown.
Date of Publication: Dec. 2012