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 1×1018 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 Å at 20 mA, respectively. The light output power of the uncoated diodes is as high as 150 μW at a dc current of 100 mA and an external quantum efficiency of 0.085%–0.10% is observed.