Electrosurface Properties Of Aiiibv Semiconductors In Water Solutions
ELECTROSURFACE PROPERTIES OF AIIIBV SEMICONDUCTORS IN WATER SOLUTIONS
V.G. Lutsenko
Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences,Palladin avenue 32-34, 03680 Kyiv, Ukraine
AIIIBV Compounds are used in various semiconductor devices whose properties depend on quality of semiconductor surface. Etching in water solutions are used for preparation of optimal surface different crystalline planes of AIIIBV semiconductors. Most of AIIIBV compounds form crystals with ZnS grate (sfalerite). Sfalerite structure and ionic component give polarity along axes . So, planes {111} of As and {111} of Ga and In are described with different properties. The main surfaces of GaAs and InAs may be characterized by {111}, {110} and {100} planes.
Therefore, for optimization of etching processes for those semiconductors we investigated interfacial phenomena between surface {111}, {110} and {100} planes and water solutions.
In our investigation we determined the points of a zero charge (PZC) {111} As, {111} Ga, {111} In and {100} planes in water solutions.
Objects of investigation were monocrystalline plates of GaAs and InAs with {111} As, {111} Ga, {111} In, {100} planes and powders, obtained by fragmentation of monocrystals. Methods of research were potentiometric acid-base titration, mass titration, optical microscopy and X-raying.
Potentiometric acid-base titration and mass titration of surface {100}, {111}, {111} planes and powders of GaAs and InAs were carried out in water solutions in nitrogen medium. The investigation of physicochemical processes on the interfacial border was determined both in the dark and at illumination of white light. (The band gape of GaAs consists of 1,43 eV and InAs is 0,46 eV). It was shown that surfaces of GaAs and InAs in water solutions are characterized by three points of a zero charge:
GaAs
pH = 5,5 ± 0,1 {111} As, pH = 9,5 ± 0,2 {1’1’1’}Ga, pH = 7,2 ± 0,1 {100}.
InAs
pH = 3,3 ± 0,2 {111} As, pH = 6,3 ± 0,2 {1’1’1’}In, pH = 4,5 ± 0,15 {100}.
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