Strain relaxation in InAs/GaSb heterostructures

Abstract

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Strained GaSb/AlAsSb quantum wells for p-channel field-effect transistors

“…It is not clear why dislocations apparently form at a lower strain in the GaSb quantum wells compared to InGaSb. One possibility is that the AlAsSb buffer layers provide a larger source of threading dislocations than the AlGaSb buffer layers [21]. If that is the case, then a substantial reduction in the dislocation density from the use of a graded buffer layer of AlAsSb could allow larger strains in the GaSb quantum well and higher mobilities.…”

Interfacial Misfit Array Technique for GaSb Growth on GaAs (001) Substrate by Molecular Beam Epitaxy

“…This technique shows several shortcomings, such as the indispensability to grow thick buffer layers (often >1 lm), poor thermal and electrical conductivity, and crucial material degradation through the formation of threading dislocations. In IMF growth mode, the strain is relieved instantaneously at the interface between the GaAs substrate and the GaSb epilayers by the formation of (2D) periodic IMF arrays consisting of pure-edge 90°dislocations along both [110] and [1][2][3][4][5][6][7][8][9][10] directions. 11 The growth of thick GaSb epilayers on GaAs substrates was considered to begin as islands and then merge to create layers, and in this consideration, both 60°and 90°misfit dislocations exist.…”

“…7 This latter is highly detrimental to the electrical and optical properties of the device structures. Several techniques have been used to mitigate this deleterious effect, including metamorphic buffer layers, 8 strain-relief superlattice, 9 and interfacial misfit dislocation (IMF) growth mode. 10 In the metamorphic buffer layer approach, the strain is accommodated through tetragonal distortion in addition to defect formation, within a critical thickness.…”

Buffer influence on AlSb/InAs/AlSb quantum wells

“…Because the calculation is based on AlSb and GaSb substrates with perfect crystal quality, it is reasonable that InAs begins to relax under the calculated critical thickness in our experiment [14]. Because of strain relaxation for InAs QW with AlSb buffer, mismatch dislocations would occur in the InAs layer.…”