Let us assume the bias is V and the barrier width is W . This probability , P , that an electron at z = NUMBER@1 -LRB- left edge of barrier -RRB- can be found at z = W -LRB- right edge of barrier -RRB- is proportional to the wave function squared , : .

Let us assume the bias is V and the barrier width is W , as illustrated in Figure NUMBER@2 . This probability , P , that an electron at z = NUMBER@1 -LRB- left edge of barrier -RRB- can be found at z = W -LRB- right edge of barrier -RRB- is proportional to the wave function squared , : .
