For each of the following situations, draw a band diagram at t = 300 k in steady-state operation. you can use any tool that you find useful to accomplish this task. you may assume all dopants are fully ionized. on the diagram, clearly indicate and label all of the following:
· ec , the conduction band minimum
· ev , the valence band maximum
· ef , the fermi energy
· eg , the band gap
· v0 , the contact potential
the diagrams must be qualitatively correct, including
· the curvature and shape of the bands, etc. in each region
· the relative widths of the depletion regions
· the position of the fermi level relative to the bands
(a) a gallium phosphide pn junction with the following properties:
band gap eg 2.26 ev
electron affinity χ 3.8 ev
intrinsic carrier concentration ni 2 · 106 cm−3
donor concentration (n-side) nd 5 · 1011 cm−3
acceptor concentration (p-side) na 3 · 107 cm−3
clearly indicate how the bands change if a forward bias of 0.1 v is applied to the device.
(b) a schottky junction between p-type gallium phosphide and silver with the following properties:
gap band gap eg 2.26 ev
gap electron affinity χ 3.8 ev
gap intrinsic carrier concentration ni 2 · 106 cm−3
gap acceptor concentration (p-type) na 3 · 1010 cm−3
ag work function φ 4.26 ev
clearly indicate how the bands change if a reverse bias of 0.1 v is applied to the device.