# Effects of Multidimensional Defects on III-V Semiconductor Mechanics

Group Members

• Nan Yang
• Sal Barriga
• Sahil Sahni
• Vivek Raghunathan

## References

Hjort, Klas, Jan Soderkvist, and Jan-Ake Schweitz. "Gallium Arsenide as a Mechanical Material." Journal of Micromechanics and Microengengineering 4 (1994): 1-13.

Navamathavana, R., D. Arivuolib, G. Attolinic, C. Pelosic, and Chi Kyu Choia. "Mechanical Properties of Some Binary, Ternary and Quaternary III-V Compound Semiconductor Alloys." Physica B 392 (2007): 51-57.

Yonenaga, Ichiro, Koji Sumino, Gunzo Izawa, Hisao Watanabe, and Junji Matsui. "Mechanical Property and Dislocation Dynamics of GaAsP Alloy Semiconductor." Journal of Materials Research 4 (March/April 1989): 361-365.

## Wiki Assignments

Problem Set 2

(a) Draw the crystal structure of GaAs, and a separate graphic which is the closest-packed plane and direction on that plane. Discuss the major differences in this structure, as compared to Si.

(b) From the data provided in Hjort's Table 1, determine the Poisson's ratio of GaAs, as compared to Si and AlAs. Discuss comparison of these predictions with experimentally reported values of nu, from open literature and databases such as matweb.com.

(c) Hjort's Fig. 2 seems to indicate a different number of independent elastic constants than your crystal structure in (a) would suggest; explain. (It's a simple explanation.)

(d) Based on your analysis of GaAs elastic anisotropy, explain (graphically and/or text) which film orientation you would aim to achieve to create GaAs films or wafers that would be maximally resistant to bending.

Problem Set 3

(b) Why do Yonenaga, et al. claim that understanding of dislocation dynamics is relevant to GaAsP studies (basic science and applications)? Please do not restate their arguments, but rather justify them through a more detailed analysis than they could consider in a paper intro.

(c) Compare the observed GaP, GaAsP and GaAs critical shear stress (followed by a sharp drop in applied stress in Yonenaga's Fig. 1) to the corresponding theoretical shear strength of these materials, and discuss possible reasons for the relative discrepancies between theoretical and experimentally observed values among these three compounds.

(d) Given the stated impurity concentrations for the compounds considered by Yonenaga, et al., determine the maximum (average) glide distance a dislocation would require to encounter a point defect.

Problem Set 5

(b) Eq. 2 of Navamathavan, et al. states an equivalence between fracture surface energy and KIC, the plane strain fracture toughness of the semiconductor films inferred from indentation cracking. From the definitions of KIC and Griffith's fracture criterion, prove whether this equation is true for a brittle material.

(c) Although they report these data in Table 3, the authors do not appear to put the results in context by comparing the calculated KIC and surface energy with values reported for these (or similar) materials via other experiments. Do this, and discuss whether you feel the characterization of these fracture properties and surface energies of the materials is valid.

(d) Why do you think the authors observed a film thickness dependence of KIC and fracture surface energy (in Table 3), if these are supposed to be properties of the material?

## Final Presentation

"Multidimensional Defects in III-V Semiconductors." (PDF)