GROWTH AND CHARACTERIZATION OF SINGLE-HETEROSTRUCTURE ALGAAS INGAP RED LIGHT-EMITTING-DIODES BY LIQUID-PHASE EPITAXY

High quality Te-doped Al0.7Ga0.3As/Mg-doped In0.5Ga0.5P on p-type GaAs substrate single-heterostructure light-emitting diodes have been reproducibly fabricated by liquid-phase epitaxy using a supercooling technique. The growth conditions and properties of the undoped and Mg- and Zn-doped In0.5Ga0.5P layers are described in detail. The strongest photoluminescence peak intensity occurs at a hole concentration of 1 x 10(18) cm-3 of the Mg-doped layer. Diodes fabricated from the heterostructure are characterized by electron-beam-induced current, current-voltage measurement, electroluminescence, light output power, and external quantum efficiency. By appropriately controlling the hole concentration of the Mg-doped In0.5Ga0.5P active layer and the electron concentration of the Te-doped Al0.7Ga0.3As window layer, the p-n junction can be precisely located at the metallurgical junction as measured by the electron-beam-induced current technique. A forward-bias turn-on voltage of 1.5 V with an ideality factor of 1.65 and a breakdown voltage as high as 20 V are obtained from the current-voltage measurements. The emission peak wavelength and the full width at half maximum of electroluminescence spectra are around 6650 and 250 angstrom at 20 mA, respectively. The light output power of the uncoated diodes is as high as 150-mu-W at a dc current of 100 mA and an external quantum efficiency of 0.085%-0.10% is observed.