Ultrasonic treatment of GaP and GaAs

Abstract

Mobile dislocations are introduced into samples of GaP:S and GaAs:Zn by uniaxial compression (ϵpl = 1 to 5%) at 820 K. As TEM investigation shows, the resulting irregular dislocation network shows a tendency to rearrangement after a long term (N ≈︁ 7 × 108) ultrasonic treatment at a frequency of 100 kHz and a temperature between 400 and 600 K. The mechanical damping and modulus defect are in good agreement with the Granato‐Lücke theory. Under fatigue conditions applied here, the dislocation structure can be changed by comparably low ultrasound stresses (σ ≈︁ 25 to 56 MPa) at low temperatures.

Dislocation cell structures in melt‐grown semiconductor compound crystals

“…Merely, one can estimate from the TEM images of dislocation networks, published in refs. [10,40], that cell diameters d of about 5 and 10 µm correlate with applied shear stresses τ of 30 and 14 MPa, respectively. Such proportions are quite comparable with those of post-deformed metals.…”

“…Dislocation cells are also a characteristic feature in post-deformed GaAs specimens showing, however, much higher dislocation densities in the region of ρ = 10 8 -10 10 cm -2 . Much work has been done on the macroscopic deformation behaviour and dislocation structure of GaAs semiconductor crystals after plastic deformation at temperatures T/T m ≤ 0.9 (T m -melt temperature = 1511 K) [8,9,10,39,40]. Important plasticity parameters were determined by these experiments like stress-deformation curves, critical resolved shear stress, dislocation multiplication and motion rates etc.…”

“…But before that much more experimental statistics is required. [10,40], InP [52] and metals [51]. The slopes for some postdeformed dielectrics [42] and the mean dependence with K = 23 after Raj and Pharr [41] are added.…”

“…Also the rough estimations obtained from the calculated von Mises stresses for different VCz crystals [35] are added. For comparison, various data from post-deformation experiments on LEC GaAs [10,40], InP [52] and metallic crystals [41,51] are compiled too. The extrapolations of some dielectrics are given as broken lines [42,53].…”

Scaling of dislocation cells in GaAs crystals by global numeric simulation and their restraint by in situ control of stoichiometry

“…However, there have been few attempts to study scaling for semiconductor compounds. Among these, mean cell diameters of d ≈ 3 and 5 m from transmission electron microscopy (TEM) examinations on post-deformed GaAs specimens [10,11] were found at τ = 30 and 14.3 MPa, respectively. Geibel [12] ascertained a correlation of d = 22Gbτ −1 for InP single crystals bended at 0.8T m (where T m is the melting point).…”