Reference no: EM132774305
Introduction, Motivation and History
Question 1. Why is the nanometer an important length scale? This is what we will look at in this course, at the fact that the properties of matter are to a large extent determined by phenomena at the nanometer scale. It is no coincidence that some of the fundamental length scales of physics and chemistry happen to be in nanometers. What is meant by length scales is that once objects are within a range of sizes, certain effects start to be noticed.
a. For example, the wavelength of waves on the surface of the sea is of the order 10 m. On a large boat, for instance, the USS Nimitz aircraft carrier which is 333 m long, would you notice those waves? Explain.
b. On the other hand, if you were in a canoe, say 5 m long, what would happen in those waves? Explain.
c. Think now of the size of an atom - around 1/10 of a nanometer. If someone threw an atom at you, would you notice? Explain.
d. If you threw an atom at another atom, would the atom notice? Do you think it has to do with the relative sizes of things or characteristic distances over which certain effects are noticed? Explain.
Question 2. Scaling can be defined as "making things smaller without invoking quantum mechanics." The magnitude of various physical parameters of a system will change as the volume of the systems is scaled down. Start with a cube of volume L3, where L is the length of a side. The number of atoms in the cube will scale with the volume. Suppose the cube contains some number of devices, such as a transistor. Start with a transistor that is 1 micron long and contains 1012 atoms.
a. Shrink the size of the transistor to 5 nanometers on a side. Now how many atoms are in the device?
b. If a device with fewer than 1,000 atoms can no longer work, will this device still be functional?
Question 3. Considering the schematic shown above, indicate the dimensionality of the various nanomaterials:
a. Thin film
b. Quantum dot
c. Carbon nanotube
d. Polycrystalline material
e. C60 molecule
f. Quantum well
Question 4. Scaling down: A pendulum oscillates with a frequency ω given by
ω = (g/l)1/2
where g is the acceleration due to gravity 9.8 m/sec2.
a. Suppose the length of the pendulum l is 1 m, and the period T = 2Π/ω is 1 sec. If you shrink the pendulum to 1 micron, how does this affect the frequency ω?
b. What is the relationship between T and l?
c. Now think of this relationship as if the pendulum represented interatomic vibrational frequency. In a general way, what does this tell you about bond interactions when you scale down the size of an object?
Question 5. Figure 1.5 shows the number of transistors vs. the year, according to Moore's Law. Note that the y-axis is not a linear scale.
Both the increasing number and the speed of transistors are consequences of their ever-shrinking size, and it is this continuing miniaturization that has driven the industry from the first four-function calculators of the 1970s to the modern laptops. What kind of scale is the y-axis, and why is it necessary to use such a scale?
Attachment:- Motivation and History.rar