Homeworks Samuelson Paper

 

read the paper at

 

http://www.physics.pdx.edu/~pmoeck/pdf/samuleson.pdf

 

check out this link for color images of the figures, courtesy of Conrado http://www.physics.pdx.edu/~conrado/Samuelson-paper/

 

and tell me in class how you liked the paper and this kind of homework assignment, OK?

 

 

What is meant by the “bottom–up” and “top-down” approaches to nanoscience and nanotechnology?                                                                                                        4 points in total

 

 

 

 

 

What limits the dimension of devices that are achievable by the top-down approach?

 

                                                                                                                                                2 points

 

 

 

 

What are Leo Esaki and Zhores Alferov are exactly credited for?

 

                                                                                                                                                2 points

 

 

 

 

Why are quantum dots sometimes called artificial atoms?

 

                                                                                                                                                2 points

 

 

 

 

What is a quantum well, how can one model it?

 

 

 

                                                                                                                                                3 points

 

 

Does GaAs have a smaller or larger band gap than AlGaAs? Hint see figure 1

1 point

 

 

 

 

What is the potential energy function one needs to input into Schrödinger’s equation in order to model an atom?                                                                               1 point

 

 

 

 

 

Are the energy levels in a hydrogen atom evenly spaced? If not, what is the spacing of the energy levels of the first and second excited states?                                                               3 points

 

                                                                       

 

 

                                                                                                                                               

 

Are the energy levels in an infinite square well evenly spaced? If not, what is the general formulae for their spacing?

 

           

                                                                                                                        2 points

 

 

 

Are the energy levels of a harmonic quantum oscillator evenly spaced? If not what is their spacing?                                                                                     1 point

 

                                

 

 

 

At which energy is the lowest energy level of a bound electron in a hydrogen atom?

 

                                                                                                                        1 point

 

 

 

 

At which energy is the lowest energy level of an electron of frequency 105 Hz in the potential of a harmonic oscillator.

 

                                                                                                                        1 point

 

 

 

 

 

What is the typical potential energy depth of a finite square well that models a semiconductor quantum well? Again consider bound states.

 

                                                                                                                        1 point

 

 

 

 

How does one construct a potential energy barrier in a semiconductor?

 

                                                                                                                                    2 points

 

 

 

 

 

How does the tunneling probability through a barrier depends on the thickness of the barrier?

 

                                                                                                                                    2 points

 

 

 

 

 

What is the main reason that top-down approaches to nanostructures had limited success?

                                                                                                                                                1 point

 

 

           

 

                                                                                                                                               

What is the Stranski-Krastanow growth mode?

 

                                                                                                                                    2 points

 

 

 

 

 

 

By which methods other than Stranski-Krastanow growth are self-assembled semiconductor quantum dots formed ?

 

                                                                                                                                    2 points

 

 

 

 

 

 

 

What are two important differences between Samuleson’s rod-like nanostructures and carbon nanotubes?

 

                                                                                                                                    2 points

 

 

 

 

 

 

How is a quantum dot inserted into one of Samuleson’s nano wires?

 

                                                                                                                                                1 point