J. Reynaud et al., BIAS STRESS STUDIES OF A-SIN-H A-SI-H MIS STRUCTURES FROM QUASI-STATIC CAPACITANCE MEASUREMENTS/, Journal of non-crystalline solids, 187, 1995, pp. 313-318
Quasistatic capacitance measurements are used to study the effect of t
hermal bias annealing where small gate bias stresses ranging from -5 V
to +6 V are applied at 200 degrees C for 15 min on top nitride amorph
ous silicon-silicon nitride MIS structures. After negative gate bias s
tresses, the C(V-G) curves (capacitance versus gate bias) are found to
be slightly shifted towards negative voltages and their shape is alte
red. The minimum of the C(V-G) curves increases with the stress amplit
ude indicating the creation of defects in the probed energy range. Aft
er positive gate bias stresses, C(V-G) curves are shifted towards posi
tive voltages without showing any significant shape changes. This indi
cates either that negative charges have been injected into the insulat
or, or that negatively charged defects have been created in the a-Si:H
layer (or at the a-Si:H/nitride interface) outside the probed energy
range (0.15-0.65 eV below the conduction band edge). The results can b
e qualitatively described by changes in the defect distribution in agr
eement with what is expected in the framework of the defect pool model
.