630-nm n-type Modulation-doped AlGaInP-AlInP multiquantum-well light-emitting diode

AlGaInP-AlInP multiple quantum-well (MQW) light-emitting diodes (LEDs) with n-type modulation-doped (MD) structure were grown by metal-organic vapor-phase epitaxy. Their characteristics were then evaluated using current-voltage (I-V), electroluminescence and output power measurements. Experimental results indicated that the LEDs exhibited a higher output power, a lower dynamic resistance, and a smaller wavelength variation than conventional LEDs. The n-type MD-MQW LEDs exhibited a higher external quantum efficiency (7.19%) and a larger maximum output power (14.84 mW) under the dc operation as compared to those of 6.73% and 12.55 mW for the conventional LEDs, respectively. This could be tentatively attributed to the better junction heating effect resulting from the n-type MD-MQW structure in which the electron thermal velocity is suppressed, especially at a high-level injection. These positive results could also be explained by the MD-MQW LED supplying a higher electron concentration than in the conventional structure.