Ln. Bolotov et al., MINORITY-CARRIERS CONTRIBUTION AND HOT-ELECTRON INJECTION PROCESS IN TUNNEL SPECTROSCOPY OF H-PASSIVATED SILICON SURFACES, Surface science, 333, 1995, pp. 468-472
Detailed studies of the current-voltage characteristics of the STM tun
nel junction with H-passivated Si(111) surfaces have been performed as
a function of type and level of doping, temperature and light illumin
ation of the surface. For slightly doped p-Si crystals we have observe
d a main contribution of minority carriers in the reverse tunnel curre
nt. For n-Si surfaces an abrupt increase of the reverse current at som
e bias voltage has been found. This effect is explained by a hole accu
mulation near the surface which changes band bending and initiates the
hot-electron injection from the STM tip with the energy sufficient fo
r the impact ionization of the carriers in the silicon. The hole accum
ulation also causes a vast hysteresis of the tunnel current. It create
s a new look at the point tunnel contact as a low-dimensional bistable
element.