The Franz-Keldysh effect in silicon–ultrathin (3.7 nm) oxide–polysilicon structures

The manifestation of the Franz–Keldysh effect was discovered when illuminated by indirect daylight Al–n+-Si:P–SiO2–(100) n-Si structures with ultrathin (3.7 nm) oxide. It has been shown that the use of backlight even at low field voltages (up to 3 V) leads to an increase in the tunneling current through the oxide compared to the current in darkness by three orders of magnitude. A model of the influence of radiation on the process of electron tunneling through an ultrathin insulating layer has been constructed. At first as a result of the Franz–Keldysh effect, a radiation quantum is captured by an electron and this charge carrier tunnels through the barrier at a higher level compared to darkness. After a charge carrier enters a semiconductor, its energy is sufficient for several events of electron–hole pair production during impact ionization of silicon.