Assignment 1: MTE 4597/5197 Available from 9.00 am, Monday, 7th September Due at 10 pm, Wednesday, 9th September 2020 TOTAL MARKS: 40 This assignment has been designed to reduce academic misconduct....

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Assignment 1: MTE 4597/5197 Available from 9.00 am, Monday, 7th September Due at 10 pm, Wednesday, 9th September 2020 TOTAL MARKS: 40 This assignment has been designed to reduce academic misconduct. The questions are very open in nature. Every student’s response should be unique. Q1. Describe steps in demonstrating a III-V semiconductor laser. HINT: Start with substrate selection. Will you choose GaAs or InP? Why? Will you use bottom-up or top-down methods or use a combination of both to grow/fabricate your semiconductor device? Why? If you decide to use epitaxy, what layers will you grow, and with what thickness? Why? Please only talk about the order of magnitude of the thickness. If you decide to use top-down fabrication, what would be your steps to get the required device structure? Please discuss the order of magnitude of the dimensions of the structures you will form using top-down fabrication. What steps will you use to form your cavity? How will you achieve population inversion (electrical pumping or optical pumping)? Why? If using electrical pumping, how will you pump electrons into conduction band? If using optical pumping, what optical source will you use? For each step, please state reasons for your choice. You will get marks only if you reason all your steps. You will get marks even if your choice is wrong, but your reasoning is correct. Marks: 20 Q2. After you fabricate your device, following the steps you outline in Q1, how will you test whether you have a laser or a light emitting diode? HINT: Think about the differences between a laser and a light emitting diode. How can you experimentally differentiate between the two devices? Will Young’s double slit experiment help? How? What do you expect from the experiments you chose? Marks - 10 Q3. Consider a GaAs/AlGaAs heterostructure as shown in the figure below. The bandgap of GaAs is 1.4 eV, and the composition of AlGaAs corresponds to a bandgap of 1.5 eV. Sketch the bandgap of the heterostructure. Sketch the expected photoluminescence (PL) spectrum from this heterostructure. Give reasons as to why the PL will look like what you have sketched. Marks - 10 GaAs AlGaAs GaAs