Band Gap Threshold Shift Scan - Semiconductor Physics and Transistor Switching Step by Step

Moving the band gap changes which photon rows are accepted.

Moving the band gap changes which photon rows are accepted. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Lower gap accepts and leaves excess

The photon stays at 6 joules. Moving the band gap to 4 joules gives accepted bit 1 and excess 2 joules.

\begin{array}{c}E=hf=2\cdot 3=6\ \mathrm{J}\\6\ \mathrm{J}\ >\ E_g=4\ \mathrm{J}\\\mathrm{accepted}=1\end{array}

Matching gap is the equality boundary

The photon stays at 6 joules. Moving the band gap to 6 joules gives accepted bit 1 and excess 0 joules.

\begin{array}{c}E=hf=2\cdot 3=6\ \mathrm{J}\\6\ \mathrm{J}\ =\ E_g=6\ \mathrm{J}\\\mathrm{accepted}=1\end{array}

Higher gap rejects the same photon

The photon stays at 6 joules. Moving the band gap to 8 joules gives accepted bit 0 and excess 0 joules.

\begin{array}{c}E=hf=2\cdot 3=6\ \mathrm{J}\\6\ \mathrm{J}\ <\ E_g=8\ \mathrm{J}\\\mathrm{accepted}=0\end{array}