The effects of oxide apertures on the characteristics of resonant-cavity light-emitting diodes

The 650nm oxide-confined RCLEDs (resonant-cavity light-emitting diodes) have been fabricated with different oxide aperture diameters. The oxide apertures, which could apply confinement of both the carrier distribution and the optical field, are created by lateral selective wet oxidation of AlAs layer in the p-DBR (distributed Bragg reflectors). All samples have the same diameter 80 mu m of the emission window defined by the circular electrodes, while their current apertures are defined by the oxidation apertures ranged from 90 mu m to 130 mu m, larger than the emission window. The maximum optical power is 1.909mW. The electrical and optical properties are systematically discussed for different oxide apertures. The greater voltage at 20mA is attained for smaller oxide-aperture devices as smaller oxide-aperture devices have greater series resistance due to the oxide layer. The maximum output power is reached rapidly for smaller oxide-aperture devices since smaller oxide-aperture devices have larger current density at the same current. The maximum output power of smaller oxide-aperture devices is lower than that of larger oxide-aperture devices. It is because that larger current density and greater series resistance could lead to greater Joule heat, which results in more injected electrons relax their energy by the way of nonradiation.