Chapter 5 Lecture - Part 6

This can lead to discontinuities in the bands at the

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ng bandgaps • There will be a difference in valence band energy levels There (ΔEv) and conduction band energy levels (ΔEc) across the across junction. • This can lead to discontinuities in the bands at the junction ΔEc = q(χ2 – χ1) and ΔEv = ΔEg – ΔEc • Ideally: Ideally: q( and • To contrast the bands of the junction, one must use a To reference so as to define the affinities. This reference is E vac reference An ideal heterojunction between a p-type, wide band gap semiconductor an n-type narrower band gap semiconductor: (a) band diagrams before joining; (b) band discontinuities and band bending at equilibrium. Heterojunctions Heterojunctions • How to create an approximate band diagram – Align the Fermi levels for either side of the junction, but Align leave space between the transition regions leave – Locate the physical junction and the terminal position of Locate each band at the junction each – Draw the bands • Significance: – Heterojunctions can be used to create potential wells in Heterojunctions the band structure the • The well can be used to quantize the energy states The • The well can also be used to increase the mobility of charge The carriers as compared with those outside the well due to negligible impurity scattering negligible A heterojunction between N+-AIGaAs and lightly doped GaAs, illustrating the potential well for electrons formed in the GaAs conduction band. If this well is sufficiently thin, discrete states (such as E1 and E2) are formed, as discussed in Section 2.4.3....
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online