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Unformatted text preview: ECE 440 Homework XVI Fall 2005 Due: Wednesday, December 07, 2005 1. Refer to Fig. 1-13. Assuming the lattice constant varies linearly with composition x for a ternary alloy, what composition of GaSb 1-x As x is lattice-matched to InP? What composition of In x Ga 1-x P is lattice-matched to GaAs? What is the bandgap energy in each case? Also, assuming that a p-n junction is made in the corresponding lattice-matched epitaxial layer and light emits in each case, which substrate is considered to be transparent? Namely, which substrate would not considerably absorb the light emitted from the p-n junction toward the substrate? 2. A monochromatic light source of wavelength 7000Å and intensity I o = 4 watts/cm 2 impinges onto a 0.2 μ m thick single crystal GaAs layer that is supported on a transparent sapphire (Al 2 O 3 ) window as shown the backside. Also shown are the absorption coefficients for several semiconductors. Adjacent to the GaAs is a 25-μm thick germanium wafer that absorbs some ofsemiconductors....
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This note was uploaded on 12/01/2011 for the course ECE 440 taught by Professor Staff during the Spring '08 term at University of Illinois, Urbana Champaign.
- Spring '08