Defect Thermodynamics and Phase Diagrams in Compound Crystal Growth Processes

Wenzl, H.; Oates, W.A.; Mika, K.

doi:10.1016/b978-0-444-88908-9.50009-7

Cited by 10 publications

(6 citation statements)

References 71 publications

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“…By analogy, we define The modelling of the solid phase relies on the sublattice model, which was introduced and described by Wenzl et al (1990Wenzl et al ( , 1993, Oates et al (1995), Hurle (1999Hurle ( , 2004. Furthermore, we assume that there are exclusively entropic contributions to the chemical potentials.…”

Section: Explicit Constitutive Model For Gaasmentioning

confidence: 99%

“…However, vacancies may also be found on the two other sublattices. A serious description of the physical and chemical properties of semi-insulating GaAs also needs to consider charged states of the introduced constituents and additionally free electrons and holes (Blakemore 1982;Wenzl et al 1990Wenzl et al , 1993Hurle 1999Hurle , 2004Gebauer 2000). free charges e h…”

Section: Constitution Of the Three Phases Of Gaas (A ) Chemical Constmentioning

confidence: 99%

“…We decompose the constitutive quantities into chemical and mechanical parts. The chemical parts rely on the well-established sublattice model that was formulated by Oates et al (1995) and Wenzl et al (1990Wenzl et al ( , 1993. The mechanical parts rely on the St. Venant-Kirchhoff law that relates the Green strain tensor to the second Piola-Kirchhoff stress tensor.…”

Section: Introductionmentioning

confidence: 99%

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On the modelling of semi-insulating GaAs including surface tension and bulk stresses

Dreyer

Duderstadt

2008

Proc. R. Soc. A.

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The necessary heat treatment of single-crystal semi-insulating gallium arsenide (GaAs), which is deployed in micro-and optoelectronic devices, generates undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid-solid interface and deviatoric stresses in the solid.The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular, the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant-Kirchhoff law, which gives an appropriate stress-strain relation for many solids in the small-strain regime. We establish criteria that allow the correct replacement of the St. Venant-Kirchhoff law by the simpler Hooke law.The main objectives of this study are the following: (i) we develop a thermomechanical model that describes diffusion and interface motions, which are both strongly influenced by surface tension effects and deviatoric stresses, (ii) we give an overview and outlook on problems that can be posed and solved within the framework of the model, and (iii) we calculate non-standard phase diagrams for GaAs above 1059 K, i.e. those that take into account surface tension and deviatoric stresses, and we compare the results with classical phase diagrams without these phenomena.

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Section: Explicit Constitutive Model For Gaasmentioning

confidence: 99%

Section: Constitution Of the Three Phases Of Gaas (A ) Chemical Constmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the modelling of semi-insulating GaAs including surface tension and bulk stresses

Dreyer

Duderstadt

2008

Proc. R. Soc. A.

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“…The redistribution of excess As to larger size precipitates for an annealing process comparable to the modified multistep annealing process has been reported [7, 81. The proposed processes are known to be critically dependent on temperature in the range T 2 900°C [9], qualitatively accounting for the observed contrast reversal within a narrow interval of annealing temperatures.…”

Section: Discussionmentioning

confidence: 97%

High resolution EL2 and resistivity topography of SI GaAs wafers

Wickert

Stibal²,

Hiesinger³

et al. 1998

Semiconducting and Insulating Materials 1998. Proceedings of the 10th Conference on Semiconducting and Insulating Materials (SI

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The mesoscopic inhomogeneity of LEC grown semi-insulating (SI) GaAs wafers has been investigated with EL2' absorption topography (EAT), photoluminescence topography (PLT), point contact topography (PCT) and contactless resistivity mapping (COREMA). Significant progress with respect to sensitivity of EAT and lateral resolution of COREMA has been achieved. High resolution topograms of wafers cut from ingots subject to standard and modified annealing procedures are presented. Direct comparison of EL2' and resistivity topograms reveals significant differences in the mesoscopic contrast and a contrast reversal for modified annealing. These observations can be explained very satisfactorily by assuming mesoscopic inhomogeneity of the intrinsic acceptor concentration which is modified during annealing. A model involving generation of Ga vacancies by dissolution of As,, antisites and gettering of the interstitial As at precipitates is presented and discussed. A. IntroductionThe macro-and mesoscopic homogeneity of liquid-encapsulated Czochralski (LEC) SI GaAs wafers has been improved in recent years by systematic optimization of ingot annealing processes. But mesoscopic fluctuations of resistivity, related to the cellular distribution of dislocations, continue to stimulate research-and application-oriented investigations, requiring topographic optical and electrical characterization techniques with high sensitivity and lateral resolution. PLT has been widely used for qualitative homogeneity assessment, although the correlation between PL intensity and resistivity appears to be incidental and often is not observed at all. Hence, high resolution, high sensitivity topograms of the resistivity itself (obtained with PCT and COREMA) and of the EL2 concentration (obtained with EAT) are needed. Evaluation of these topograms not only qualifies the material, but also allows elucidating details in the defect redistributions and the resulting changes of the compensation processes. B. Experimental DetailsThe EL2' absorption topography [l] has been enhanced in sensitivity to obtain precise mapping of concentration variations down to 1% with a lateral resolution of 30 pm. Mesoscopic resistivity mappings with comparable lateral resolution can be achieved by PCT [2]. We have implemented this technique and corroborated its reliability by direct comparison with measurements of the Bergakademie Freiberg group [3] and with COREMA measurements. The non-contacting resistivity technique COREMA [4] thus far offered a lateral resolution of about 2.5 mm, insufficient for mesoscopic investigations. We have achieved an improvement of three orders of magnitude by designing a 80 pm diameter capacitive probe with upgraded measurement circuitry. Using the same step size of 30 pm as PCT, the topograms can be directly compared. For large cell structures in the mm range, the relative variation of conductivity is comparable for PCT and p-COREMA. As will be shown below, mesosocopic variations on a smaller scale encountered in LEC grown material are somewhat u...

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“…Native point defects are realized by deviations from stoichiometry [190]. No reliable information is available for InP.…”

Section: Precipitates and Inclusionsmentioning

confidence: 99%