Physics · Ch 14 — Semiconductors
Reverse biased diode
Reverse biased diode
A diode is REVERSE BIASED when its anode (p-side) is connected to the negative terminal of the external voltage source and its cathode (n-side) to the positive terminal. Under reverse bias, the width of the depletion region INCREASES, and the junction behaves like a HIGH resistance (Fig. 14.25): practically no current flows as the reverse bias voltage is increased, though a very small leakage current -- of order a few microamperes -- still flows, carried by the small number of thermally generated minority carriers that continue to drift across the junction. …
What this figure shows. A diagram of the p-n junction diode connected in reverse bias (positive terminal to the n-side/cathode, negative terminal to the p-side/anode), showing the depletion region drawn distinctly WIDER than its zero-bias width. The widened region is depicted as offering a HIGH RESISTANCE path across the junction, consistent with the surrounding text's statement that reverse bias increases the width of the depletion region so that practically no current flows except a very small leakage …
What this figure shows. A graph of reverse current (vertical axis) against reverse voltage (horizontal axis) for a diode. For increasing reverse voltage over most of the plotted range, the curve stays very close to the horizontal axis, showing only a small, nearly constant leakage current. At a particular, comparatively large reverse voltage, the curve suddenly bends and rises SHARPLY -- this sudden steep rise marks the onset of AVALANCHE BREAKDOWN, the point at which the junction overheats, covalent bonds break down, a large number of additional carriers become available, and the dio …