Properties of GaP Green-Light-Emitting Diodes Grown by Liquid-Phase Epitaxy

Abstract

Efficient and reproducible green‐light‐emitting diodes have been made by a vertical liquid‐phase epitaxial method. External quantum efficiencies of uncoated diodes as high as 3×10⁻⁴ at 300°K were obtained. The I‐V characteristics of these diodes show an exponential behavior of the form I = I₀ exp eV/βKT; values of β were generally about 2 at 300° and 77°K. The emission intensity varies with I² at low currents, and changes to an approximately linear dependence at high currents. Emission spectra have been studied as a function of current and temperature from 27° to 670°K. Seven emission lines in the green region of the spectrum have been observed, and the origins of these radiative recombinations have been studied. At low temperatures, four lines are identified as pair emission. One line at intermediate temperatures is believed to be due to free‐hole‐to‐donor emission, and two lines at high temperatures may be attributed to free‐exciton recombination.