DIFFUSION OF IRON INTO GAAS FROM A SPIN-ON SOURCE

Iron was diffused from a spin-on glass film into n-type GaAs wafers at temperatures of 700°–900°C. The observed diffusion depths can be explained by a model with exhaustible diffusion sources. The diffusion coefficient of iron in GaAs has been estimated to be 1 × 103 exp (−2.7/kT) in this temperature range. The resistivity of the diffused layer was in the order of 104 Ω cm. The activation energy of the introduced levels was 0.53 eV for the diffusion at 700° and 800°C, which agrees well with the acceptor level of iron. The current-voltage characteristics of mesa diodes made of the diffused wafers showed no excess leakage current, which ensures that high-resistivity, p-type, iron-diffused regions can be used for junction isolation in GaAs integrated circuits. © 1990, The Electrochemical Society, Inc. All rights reserved.