THERMODYNAMIC-EQUILIBRIUM KINETICS OF PHOSPHORUS AND BORON-DOPED A-SI-H

Thermodynamic equilibrium kinetics of phosphorus (P) and boron (B) doped hydrogenated amorphous silicon (a-Si:H) are explored using dark conductivity measurements. Small variations in temperature of the semiconductor cause variations in active dopant concentration, which affects the conductivity. The equilibration kinetics of phosphorus- and boron-doped a-Si:H are different and there is a strong dependence on the deposition temperature (T-s). The transformation of P into the electronically active phase (activation) follows a stretched exponential time dependence with a temperature-independent dispersion parameter, beta, of 0.85, whereas the transformation into the electronically passive bonding configuration (passivation) is also a stretched exponential but with beta less than or equal to 0.8. The kinetics of boron metastability are similarly a stretched exponential, but with equal beta values for activation and passivation. The time constant, tau, to achieve equilibrium for both transformations is thermally activated with energies E(act) similar or equal to 1.1 eV for P and B. An increase in T-s leads to an increase of E(act).