Modeling Recombination at the Si–Al$_{2}$O $_{3}$ Interface

In this paper, we present a complete set of data on the silicon surface passivation parameters of Al
₂
O
₃
deposited by atmospheric pressure chemical vapor deposition with triethyldialuminum-tri-( sec-butoxide) and H
₂
O precursors at temperatures between 325 and 520°C. Using measured values of the total interface charge
Q
_tot
and of the interface defect density
D
_it
(
E
), apparent electron capture cross section σ
_n
(
E
), and apparent hole capture cross section σ
_p
(
E
) as a function of the energy within the bandgap
E
, we calculate surface recombination velocities using the Shockley-Read-Hall (SRH) model and compare these with measured values, finding excellent agreement when
Q
_tot
is large and reasonable agreement otherwise. The resulting model is valid for both n- and p-type substrates, under the condition that holes are the majority carrier at the surface, as is generally the case for typical (negative) values of
Q
_tot
. It is shown that, under these conditions, recombination is dominated by a single donor-like defect species located just below midgap. These results support the direct correspondence between
Q
_tot
,
D
_it
(
E
), σ
_n
, and σ
_p
determined by capacitance and conductance measurements of metal-insulator-semiconductor structures and the carrier lifetimes measured by photoconductance.