High-power LEDs based on InGaAsP/InP heterostructures

High-power light-emitting diodes (LEDs) with mesa diameters of 100, 200, and 300 $\mu$m are developed on the basis of InGaAsP/InP heterostructures. The mesas are close in shape to a truncated cone with a generatrix inclination angle of $\sim$45$^\circ$ in the vicinity of the active region of the LED, with a ring etched around the mesa serving as a reflector. The emission spectra and directivity patterns of these LEDs are studied in a wide range of current densities and it is shown that radiative recombination is dominant to a current density of $\sim$5000 A/cm$^2$, which makes these structures promising for the development of high-power LEDs. An emission power of $\sim$14 mW is obtained in the continuous-wave mode ($I$ = 0.2 A, $\lambda$ = 1.1 $\mu$m), and that of 77 mW, in the pulsed mode ($I$ = 2 A, $\lambda$ = 1.1 $\mu$m), which corresponds to external quantum efficiencies of 6.2 and 3.4%, respectively.