Band Diagrams for Semiconductor Heterostructures

The upper half of this Java applet lets you move, relative to the vacuum level, the conduction band, valence band and Fermi level of the two constituents of a heterojunction by dragging the labels Ec, Ev and Ef up and down. Dragging the equal sign to the right of each band diagram moves the conduction band and the valence band together, keeping the bandgap constant. The lower half gives the band diagram for the heterojunction. You can apply a voltage by dragging the Fermi level apart in the lower half. When the voltage is nonzero, the polarity of the bias is indicated by + and - signs.

The depletion width does not change with doping (Fermi level) in this version. This may be incorporated in the future.