MIT OpenCourseWare http://ocw.mit.edu 3.22 Mechanical Properties of Materials Spring 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms .Group: Effects of multidimensional defects on III-V semiconductor mechanics PS2 part b work detailing calculations of Young’s modulus We use the following equation to solve for Young’s modulus in the different directions: 1 1 = S11 − 2[(S11 − S12) − S44][α2β2 + α2γ2 + β2γ2]E[hkl] 2 From the review article we see that 1 E<100> = = 8.547x1010Pa S11 and using α = β = γ = √13 E<111> = 1.422x1011Pa for α = β = √12 in the < 110 > direction E<110> = 1.22x1011Pa We conclude that the < 111 > direction is the direction with the highest Young’s modulus, hence it will be more resistant to stretching in the direction.
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