Method of preparing semiconductor substrates
AssigneeMax-Planck-Gesellschaft zur Foerderung der Wissenschaften e.V.
InventorsHans Fronius, Albrecht Fischer, Klaus Ploog
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Abstract
A new method for GaAs substrate preparation which significantly reduces the ormation of oval defects during MBE growth of selectively doped n-Al.sub.x Ga.sub.1-x As/GaAs heterostructures. The method simply requires treatment in H.sub.2 SO.sub.4 after mechano-chemical polishing in NaOCl solution and generation of a protective surface oxide during in soldering. Routinely a density of oval defects of less than 200 cm.sup.-2 is achieved for 2-.mu.m thick heterostructures. The efficiency of the new preparation procedure is demonstrated by 2DEG mobilities in excess of 10.sup.6 cm.sup.2 /Vs at 6K obtained with a spacer width as narrow as 18 nm.
Claims11
A method of preparing semiconductor substrates to reduce the formation, in particular of oval defects, during subsequent growth of semiconductor structures thereon, in particular growth of heterostructures by molecular beam epitaxy, wherein the substrates are chemically cleaned and are provided with a thin oxide layer as protection against contamination during handling prior to growth of a said semiconductor structure thereon, characterised in that the substrate is first subjected to mechano-chemical etch polishing using an abrasive free fabric or paper polishing lap soaked with an oxidising etching solution and is then treated by placing it in a concentrated acid, in particular H.sub.2 SO.sub.4 subjected to agitation.
Dependencies are inferred from the claim text.