Planar beam Lead GaAs electroluminescent arrays

Planar and beam lead technologies have been successfully combined in GaAs for the first time with the batch fabrication of four by four matrix arrays of electroluminescent diodes. The diodes are Zn-diffused on 10 mil centers with Zn-masking being provided by a composite structure of thermally deposited SiO2and phosphosilicate glass layers. The deposit of a continuous layer of-SiO2after pattern definition but before Zn diffusion minimizes both the lateral diffusion ard the high leakage current that can occur in deep-diffused GaAs planar structures. Beam lead technology is used for contacting both the n and p regions on the same side of the GaAs slice. After the back is polished to a final slice thickness of less than 2 mils, the arrays are etched out, with the beam leads acting as structural and electrical bridges across the etched out areas. Quantum efficiencies for light emitted through the backs of the units are typically 0.2% with excellent uniformity from diode to diode. Array yields are such that larger arrays are considered to be feasible. The arrays show considerable promise both for switching and for memory applications.