Development of a vertical gradient freeze process for low EPD GaAs substrates

Investigation of residual dislocations in VGF-grown Si-doped GaAs

“…Apart from the low-temperature gradient also the dopant silicon contributes to the lowering of the EPD due to its lattice hardening effect. EPDs of nominally undoped VGF-GaAs typically range in the order of some 1000 cm À2 whereas in Si-doped material, EPDs of some 100 cm À2 and below [4,5] are achieved.…”

Crystal growth of compound semiconductors with low dislocation densities

“…A pre-treatment of the substrate by in-situ HCI-etching (sample 2), separate annealing (sample 5) or reactive ion etching (sample 7) are less efficient than KOH etching (sample 4). The same also holds for the variation of a single epitaxial growth parameter such as growth rate~(sample 8:~= 6.7 flm/h; sample 9:~= 27 flm/h); C/Si ratio (sample 11: C/Si = 0.75; sample 12: C/Si = 1.5) or doping (sample 14: [N] ""' 10 17 cm- 3 ; sample 15: [AI] ""' 10 14 cm-3). However, it is possible to achieve outstanding conversion ratios of BPDs which are comparable or even better than for KOH etching by applying a combination of well suited epitaxial parameters only (see sample 16).…”

“…2]. Nowadays Si-doped GaAs crystals with diameters of 4 inch and larger and EPDs significantly below 100 cm-2 [2,3] are commercially available.…”

Structural properties of pressure-induced structural phase transition of Si-doped GaAs by angular-dispersive X-ray diffraction

“…However, we believe that it might have something to do with defect activities inside the crystals. Usually, in VGF-grown Si-doped GaAs crystals, several types of dislocations resulting from thermal stress and/or lattice mismatch during growth process have been identified in the previous works [2,[29][30][31][32][33]. Birkmann et al [2] pointed out that the 60°dislocations belonging to the f111g 1 2 \110 [ glide systems were the most common dislocations in materials with zinc-blende structure.…”