Nanotechnology Questions and Answers – Nano Electronics

This set of Nanotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Nano Electronics”.

1. Choose the correct statement from the give options.
a) Quantum Cellular Automata (QCA) provides an interconnected method of information exchange
b) Basic operation of a spin device depends on the anti-ferromagnetic materials
c) Quantum computing avoids the usage of interference properties of entangle quantum mechanical particles
d) High cost of CMOS fabrication plants is due to the non-defect tolerant lithographic fabrication methods
View Answer

Answer: d
Explanation: The basic operation of a spin device depends on the ferromagnetic materials having multiple one spin close to the Fermi energy or surface. Quantum cellular automata (QCA) provide an interconnect less method of information exchange and computation. Quantum computing uses the interference properties of entangle quantum mechanical particles to allow each qubit in the computer to be intimately linked to every other qubit of the system. The real reason for high cost of CMOS is the use of lithographic fabrication techniques that are not defect tolerant.

2. Who were the developers of the first MOSFET?
a) Cyrus Tabery and Jakub Kedziersk
b) Dawon Kahng and Mohamed Atalla
c) Nick Lindert and Toru Kang
d) Eiji Takada and Shibly Ahmed
View Answer

Answer: b
Explanation: The first MOSFET (metal oxide semiconductor field-effect transistor) was developed by Egyptian engineer Mohammed Atalla and Korean engineer Dawon Kahng at Bell Labs in 1960. They fabricated the MOSFET having a gate oxide thickness of 100nm, along with a gate length of 20μm.

3. Identify the types of set memory that is a miniature version of CMOS flash memory found in phones and MPEG music stick players.
a) Gate memory
b) Miniature flash memory
c) Yano-type memory
d) Coulomb blockade
View Answer

Answer: b
Explanation: This type of set memory is very similar to a CMOS flash memory and can be regarded as its miniature form. They find their applications in mobile phones and (MPEG) music stick players. One downside to this this type of set memory is the robustness of the memory nod to stray charge and fluctuations.

4. Which of the following is not an advantage of nanowires?
a) High electron mobility
b) Shorter response time
c) Greater dielectric constant
d) Asymmetric electron-hole characteristic
View Answer

Answer: d
Explanation: Nanowires have high electron mobility, high dielectric constant, and a symmetrical electron-hole characteristic. Their extremely high surface to volume ratio of thin 1D nanostructure has enabled them to function well with high sensitivity and short response time. They even allow several transistors to be packed into a single chip leading to a more uniform and compact structures.

5. Esaki diodes use only one type of charge carriers during their operation.
a) True
b) False
View Answer

Answer: b
Explanation: Esaki diode or tunnel diode is a semiconductor diode that has effective “negative resistance” due to the mechanical effect called tunneling. These diodes utilize only one type of charge carriers – either electrons or holes. These diodes form an interband device where electrons tunnel from the conduction band to hole states in the valence band.

6. What is the major downside to Yano-type Memory?
a) Robustness of the memory node
b) Little or no amplifications
c) Mass production of the memory devices
d) Scalability of the circuits
View Answer

Answer: c
Explanation: Yano type memory faces the challenge of conduction in the channel. This is due to a percolation path through a great amount of poly-Si grains. This process is uncontrollable and very random in nature. Thus, the mass production of these memory devices with required regulatory properties seems to be an obstacle in this approach.

7. Why are super-miniature electronic ICs fully functional at nanoscale while mechanical devices are not?
a) Greater volume
b) Greater friction
c) Greater surface area
d) Greater power
View Answer

Answer: b
Explanation: The power of any machine is proportional to its volume whereas the friction is dependent on the surface area. In case of a regular sized machine, power is enough to overcome any friction. However, at nanoscale the friction overcomes power. This is because the volume of an object decreases as the third power of its dimensions while the surface area only decreases as the second power. Thus, the machines at nanoscale become redundant.

8. Why does a p-n junction stop electrons from being transported through a system?
a) Formation of depletion layer
b) Presence of very high voltage
c) Absence of impurities in silicon
d) Swift transportation of electrons
View Answer

Answer: a
Explanation: When p-type silicon is placed inside an n-type piece of silicon, a depletion layer is formed. Here the electrons and holes annihilate each other and prevent the flow of electrons between the two regions unless a large voltage is applied between them. Therefore, a p-n junction fails to transport electrons within the system.

9. Who proposed molecular electronics?
a) Ari Aviram
b) Gordon Moore
c) C.N.R. Rao
d) James Chadwick
View Answer

Answer: a
Explanation: The concept of using a molecule as an electronic component was first proposed by the IBM researcher Ari Aviram and the theoretical chemist Mark Ratner in the year 1974. They proposed of a theoretical molecular rectifier that would be composed of donor and accepter sites which remain insulated from one another.

10. How can the transmission coefficient (T) be expressed for electrons undergoing quantum mechanical tunneling?
a) T ≈ H/16E
b) T ≈ (16H/E)e-2αb
c) T ≈ E/16H
d) T ≈ (16E/H)e-2αb
View Answer

Answer: d
Explanation: Quantum mechanical tunnel devices rely majorly on the ability of electrons to tunnel through the barriers. The transmission coefficient (T) for such electrons having energy (E), tunneling through a barrier of height (H) and thickness (b) is given by: T ≈ 16E/He-2αb.

11. What is Qubit?
a) Spin dependent tunneling of electrons
b) Crossbar switch based electronics
c) Non-volatile main memory for PCs
d) A basic unit of quantum information
View Answer

Answer: d
Explanation: Qubit or quantum bit is referred to as the basic unit of quantum information. The term was coined by Benjamin Schumacher. The quantum computers have qubit memory space for several computations at the same time. This improves the system to a great extent.

12. How does the ciliary movement of micro-organisms occur?
a) Using normal frictional forces
b) Using buoyant forces
c) Using laminar forces
d) Using casimir forces
View Answer

Answer: c
Explanation: Many microorganisms have developed cilia on their body to help them make movements. These cilia work as a machine in aqueous environments at the nanoscale. The cilia develop motion from the exaggerated drag or laminar forces (frictional forces parallel to the surface) that act at nano-dimensions.

13. Why are Quantum dot lasers preferred to traditional semiconductor lasers?
a) QD lasers have surface defects
b) QD lasers have reduced electron-phonon interactions
c) QD lasers have narrow emission line
d) QD lasers have multiparticle Auger recombination
View Answer

Answer: c
Explanation: Quantum dot lasers are often preferred to traditional semiconductor lasers. This is because emitted wavelength depends on the diameter of the dots. Moreover the QD lasers are cheaper, show improved temperature stability and narrow emission line. They also have higher beam quality and low lasing thresholds than the traditional semiconductor lasers.

14. Who was the first manufacturer of Esaki diodes?
a) Sony
b) Samsung
c) Nantero
d) Hewlett Packard
View Answer

Answer: a
Explanation: During their working tenure at Tokyo Tsushin Kogya, Leo Esaki, Yuriko Kurose and Takashi Suzuki invented the tunnel diode or Esaki diodes in August 1957. This company is now well known by the name Sony. The first esaki diodes happened to be manufactured by this company in the year 1957.

15. Choose the correctly matched pair from the following.
a) Nanophotonics – study of transport of ions
b) Nanoionics – study of quantum mechanics
c) Nanomechanics – study of electronic components
d) Nanolithography – science of etching and writing on a surface
View Answer

Answer: d
Explanation: Nanolithography refers to the science of etching, writing or printing on a material surface in the nanoscale in order to modify it. Nanophotonics deals with the behaviour of light and devices using such behaviour at nanoscale. Nanoionics is the study of ion transmission in the nanoscale systems. Nanomechanics is the branch of science studying mechanical properties of physical systems at the nanoscale.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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