Etching of Dislocations on the Low-Index Faces of GaAs

Abstract

A new etchant for GaAs consisting of CrO3, HF, AgNO3, and H2O is described which selectively attacks dislocations on the following planes: Ga {111}, As {111}, {100}, and {110}. Dislocations normal, inclined, and parallel to the plane of observation are revealed. The etching figures were correlated with dislocations by equating (a) the etch pits produced on {111} surfaces with those produced by a known dislocation etchant, (b) the {111} etch pits with the linear structure appearing on {100}, and (c) the pits on two matched {110} cleavage planes. Supporting evidence obtained from plastic indentation experiments on {111} and {100} is also presented. It is observed that long, straight dislocations tend to lie in 〈110〉 and 〈112〉 directions. It was established by reverse bending experiments that the etchant produces pits only at As or β dislocations, if no impurity segregation has occurred. If decoration of the dislocations has occurred, as in Bridgman-grown GaAs, pits are produced at both α (Ga) and β dislocations. The relative etching rates for the {100}, Ga {111}, {110}, and As {111} faces are 1.0, 0.71, 0.69, and 0.50, respectively. Stacking faults on {100} are also revealed by the etchant on epitaxial films. A second etchant is reported which reveals stacking faults on the As {111} faces of GaAs. This etchant is the same as the dislocation etchant but with the CrO3 absent.

Comparison of the Stability of Functionalized GaN and GaP

“…[9,25,26] Their natural stability provides a platform for chemical sensors, [27] solar technology, [28] and biological sensors. [29,30] Fabrication for GaN and GaP applications is limited to extreme acidic and basic conditions [31] as well as energetically driven environments [32,33] via etching solutions of molten KOH, [34] NaOH, [32] phosphoric acid, [35] sulfuric acid, [26] or nitric acid.…”

The identification of faulted prismatic dislocation loops in single crystals of undoped InP

“…It should be noted that for the {1 1 1 } slices, only the {1 1 1}P face can be examined as no chemical polish is known for the {1 1 1}In face. The {1 00} and {1 1 1}P faces were then etched in either Solution H [8] (electronic-grade 0rthophosphoric acid and hydrobromic acid in the volume ratio 2:1) or Solution AB [9] (1 g chromium trioxide, 8 mg silver nitrate dissolved in 2 ml of de4onised water and 1 ml of hydrofluoric acid) under conditions defined in detail elsewhere [1]. A postetching treatment in 10 vol % hydrochlori c acid in water was introduced to remove the residue left on the surface by Solution AB.…”

Growth of Gallium Arsenide

“…This structure is complex and is best revealed by specialized chemical etching of the surface (Abrahams andBuiocchi, 1965, Blunt et al, 1982) or reflection X-ray topography (Lang, 1978). Each technique reveals; classical dislocation cells, 'lineage' (the boundary between sections of the crystal that have a small tilt misorientation and caused by dislocation motion) and residual slip that has not resulted in polygonization, possibly because it occurred at lower temperatures.…”