Gallium arsenide-phosphide visible lamps and arrays

This paper describes the fabrication and properties of forward biased GaAsP electroluminescent lamps and arrays. GaAsP, suitably doped with selenium, is grown as an epitaxial layer on GaAs substrates using the arsine-phosphine system. Planar techniques are then employed to fabricate the p¿n junction by the diffusion of zinc into the epitaxial layer through a silicon dioxide mask. When forward biased these devices emit light at a wavelength lying in the range 660¿690 nm, depending on the alloy composition. With an operating voltage of 1.7 V and a current density of 25 A/cm2 (30 mA for 0.38 mm diameter devices), lifetimes up to 7000 hours have been measured with little deterioration in light output. By connecting the lamps on the epitaxial slice with a system of evaporated leads, 5×7 arrays have been made giving an alpha-numeric symbol within a rectangle measuring 6.1×8.6 mm.