The distribution of potential in the space charge region of a @[email protected] results in a change in the electron energy levels with distance from the @[email protected] This is usually described as 'bending of the energy bands'. Thus the bands are bent, upwards if \(\sigma >0\) and downwards if \(\sigma <0\), where \(\sigma \) is the free @[email protected] When \(\sigma =0\) the condition of flat bands is met, provided no @[email protected] are present.