Anodic oxidation of GaAs is examined and a technique for growing full surface oxides ~ 86G,0A thick is reported. Anodization in a hot, concentrated (30%) H202 electrolyte of pH ~-2 using self-anodizing metal contacts is found to yield uniform oxides with a refractive index of 1.8 and a growth rate ranging from 22 to 50 A/V. The as-grown oxide will etch in HC1 and H20. Chemical stability of this oxide is enhanced with baking in dry nitrogen and after 2 hr at 250~ H20 will no longer etch the oxide; after 1 hr at 600~ HC1, HF, HNO3, NI-I4OH will not etch the oxide but hot HsPO4 will etch the oxide. The oxide is an amorphous, vitreous film which crystallizes to ~-Ga20~ after several hours at 800~ A thin (<100A) graded, oxide-GaAs interface was found to grow at anodization potentials >100V and for heat-treatment at temperatures greater than 400~ for 1 hr. The oxide exhibits excellent adherence to the substrate, has good match with the thermal coefficient of expansion of GaAs, and forms a relatively strain-free interface. Since GaAs is consumed during anodization, this provides a technique for surface cleaning using an oxide growth-strip step. Enhanced device reliability is expected to result by utilization of the oxide growth-strip-regrowth cycle during device fabrication, since this will remove contamination from the surface. The findings here enumerated, coupled with ease of oxide growth, suggest ready implementation to a GaAs planar technology.

Es wird eine Methode zur vollständigen Anodisierung von GaAs‐Oberflächen bis zu einer Oxidschichtdicke von ≈︁ 8600 Å entwickelt.

This paper reports the first use of an amorphous native oxide on gallium arsenide to mask against zinc diffusion. Anodic oxides were grown at low temperature (≤100°C), and stripes were defined in this oxide using standard photolithographic processing. These samples were diffused, after an appropriate annealing cycle, in a closed system using a zinc source ( Zn 3 As 2 + GaAs ) at 612°C for times up to 2 hr. Diffusion depths were measured using a lap and stain procedure, and the results showed the oxide to be effective as a zinc barrier. Furthermore, no anomalous lateral underdiffusion was observed indicative of a high integrity interface between the oxide and semiconductor.

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