Quantum Line

1
Quantum Line Well Devices

• Diederick Spee
• Device Physics
• 27-6-2007

2
Outline

• Introduction
• Resonant tunneling diode
• Resonant tunneling transistor
• Wire vs. Well
• Quantum cascade laser
• Conclusions and prospects

3
Introduction

• Although transistors kept shrinking in the last
  decades quantum mechanics will soon inhibit
  further reduction of transistor size
• For continuing miniaturization we need device
  design that takes advantage of quantum effects

4
Introduction

• When electrons are confined their possible
  energies will be discrete
• Use this energy levels instead of band gap of the
  semiconductor
• When devices are designed to resemble existing
  devices, there may come interesting features with
  it

5
Resonant Tunneling Diodes
6
Resonant Tunneling Transistors
7
Wire vs. Well

• In a wire the island will have truly discrete
  energy levels
• Wires are difficult to fabricate
• Bottom up difficult for multiple materials
• Top down lots of defects caused by etching
• Wells are already used because they are easier to
  fabricate

8
Resonant tunneling diode in one molecule
9
Quantum Well Devices

• Usually multiple quantum wells are used to
  increase effect
• These heterostructures are already used to build
  diodes
• Example of succesful use quantum cascade laser

10
Quantum Cascade Laser
11
Conclusions and Prospects

• Replacing existing devices by quantum well and
  line devices in theory quite well possible
• Difficult to fabricate 1D devices , which are
  necessary for totally discrete electron levels
• 2 D devices are already used with succes