Special Problem (20 pts) Consider an undoped AljGa7As/GaAs/ Al3Ga7As quantum well (QW) of width W...
2. (a) Assuming Anderson's rule and Vegard's law calculate the depth of the confining potential in meV, for holes in the valence band of a InAs/InxGa1-xAs multi QW structure where x-0.5. [5] State whether electron and hole confinement is within the InAs or InGaAs layers, and hence deduce what type of structure/band alignment this is. Suggest why this structure might be difficult to grow experimentally. (b) A Gao.47lno.53As quantum well laser is designed to emit at 1.55um at room temperature...
(b) Flgure 3 shows an ideallsed schematic of a PL and PLE spectrum at 4.2K from a GaAs/AIGaAs multi QW (MOW) structure. Assuming the excitation power is low, and assuming the Infinite well approximation, estimate; ü) the width of the well in nm (l) the exciton binding energy in the well With reasoning, state whether thls calculated well width would be an upper or lower limit to the well width in a real GaAs/A GaAs MQW 2] This MQW structure...
Quantum Mechanics Problem 1. (25) Consider an infinite potential well with the following shape: 0 a/4 3al4 a h2 where 4 Using the ground state wavefunction of the original infinite potential well as a trial function, 2πχ trial = 1-sin- find the approximation of the ground state energy for this system with the variational method. (Note, this question is simplified by considering the two components of the Hamiltonian, and V, on their own) b) If we had used the 1st...
4. (20 points) Infinite Wells in Three Dimensions a) Consider a three dimensional in- finite rectangular well for which L -L, Ly-2L, ald L2-3L. In terms of quantum numbers (e.g. nz, ny, and n.), M. L, and ћ. write down an expression for the energies of all quantum states. (b) Find the energies of the ground state and the first three lowest lying energies. As in part (b), for each energy level, give the quantum numbers n, ny, n and...
2. Goal of this problem is to study how tunnelling in a two-well system emerges. In particular, we are interested in determining how the tunnelling rate T' of a particle with mass m scales as a function of the (effective) height Vo - E and width b of an energy barrier separating the two wells. The following graphics illustrates the set-up. Initially the particle may be trapped on the left side corresponding to the state |L〉, we are now interested...