2. a) Draw the resultant energy band diagram with proper levels at equilibrium when a heterojunction is made between two semiconductors A and B (as shown below) where the semiconductor A is n-type and B is intrinsic type. E0 x1 ECA Eg = 1.8 eV EVA A x2 ?Ec = 0.23 eV ECB Eg = 1.42 eV EVB ?Ev = 0.15 eV B b) A metal with a work function of 4.6 eV has been deposited on Si (electron affinity of 4 eV) to make a contact. The Si is doped with donors with a doping concentration of 10^18 cm^-3. Draw the equilibrium energy band diagram and show the Fermi level, the band edges, and the vacuum level. Is this a Schottky or ohmic contact, and why? c) If a different metal with a work function of 3.6 eV is used to make the metal- semiconductor contact with the same semiconductor material, then what type of contact will be formed and why? Draw the equilibrium energy band diagram and mark off the Fermi level, the band edges, and the vacuum level.
Added by Joseph R.
Close
Step 1
- Semiconductor A is n-type with a conduction band offset (\( \Delta E_C \)) of 0.23 eV and a bandgap (\( E_g \)) of 1.8 eV. - Semiconductor B is intrinsic with a bandgap (\( E_g \)) of 1.42 eV and a valence band offset (\( \Delta E_V \)) of 0.15 eV. Show more…
Show all steps
Your feedback will help us improve your experience
Madhur L and 57 other Physics 103 educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Problem 4: Non-Uniformly Doped Semiconductor A silicon sample maintained at 300K is characterized by the energy band-diagram below: a) Do equilibrium conditions prevail? How do you know? b) Sketch the electrostatic potential V(x) inside the semiconductor as a function of x. c) Sketch the electric field Ɛ(x) inside the semiconductor as a function of x. d) Suppose the carrier pictured in the diagram moves between x = 0 and x = L without changing its total energy. Sketch the kinetic energy and potential energy of the carrier as a function of x. e) Roughly sketch n and p versus x f) On the same set of coordinates, make a rough sketch of the electron drift-current density and the electron diffusion current density as a function of position. For each drawing, briefly explain how you arrived at your sketch.
Adi S.
A metal contact to a n-type semiconductor can be considered as a p-n junction with NA and Np. Draw an energy band diagram of the contact showing the Schottky barrier e and the depletion width d. Then draw the energy band diagram in forward and reverse biased conditions. Indicate how the +V or -V bias affects the contact potential and the depletion width. Explain how the bias changes the forward current due to the injection of electrons from the semiconductor into the metal, and the reverse current Io from the flow of metal free carriers into the semiconductor. Show that the rectifying behavior is just like that in a p-n junction.
Manish J.
3. A step pn junction diode is made in silicon with the n-side having N'D = 2 x 10^16 cm^-3 and on the p-side the net doping is N'A = 5 x 10^15 cm^-3. a) Sketch the energy band diagram of the junction at equilibrium. Electron energy Distance (x) b) Find the built-in voltage, and compare to the value measured off your drawing in part (a). c) Find the junction width. d) Find the width of the n-side of the depletion region and the p-side of the depletion region, and the voltage dropped across each side of the transition region. e) Draw the energy band diagram for Va = 0.5 V. f) Draw the energy band diagram for Va = -5 V.
Sri K.
Recommended Textbooks
University Physics with Modern Physics
Physics: Principles with Applications
Fundamentals of Physics
Transcript
Watch the video solution with this free unlock.
EMAIL
PASSWORD