Process for making III-V devices
AssigneeVarian Associates, Inc.
InventorGeorge A. Antypas
Life of this patent
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Abstract
A very thin high quality active layer of a III-V material such as GaAs is formed on a temporary substrate on which an etch-resistant stopping layer of a material such as AlGaAs has been previously formed. Passivating layers are formed on the active layer, and the active layer is interfaced with a material which forms a permanent substrate. The temporary substrate is etched away with an etchant which is stopped by the stopping layer, following which the stopping layer is removed by etching with HF. The material in the active layer acts as a chemical stop for the HF, and consequently the etching process stops automaticaly at the boundary of the active layer, leaving that layer in the thin high-quality form in which it is grown. The etching rate of the stopping layer can be controlled by the proportion of Al in that layer.
Claims6
In a process for making a photocathode device for providing free electrons in response to incident photons, the steps of:
- providing a temporary substrate of GaAs, forming a stopping layer of AlGaAs on the temporary substrate, forming on the stopping layer an active layer of GaAs for delivering free electrons in response to photons incident thereon, forming a passivating layer of AlGaAs on the active layer, bonding the temporary substrate and the layers to a photon transparent substrate with the passivating layer closest to the transparent substrate, removing the temporary substrate, and effecting removal of the stopping layer by etching with HF.
Dependencies are inferred from the claim text.