Conductance measurements on p -Si/SiO2 metal-oxide-semiconductor capacitors

The admittance of a metal–insulator–semiconductor tunnel contact is evaluated considering the presence of donor–acceptor mixed interface states and chemical reaction in the interfacial oxide layer. Both the voltage and frequency behavior of the device has been studied. It has been found that, due to interface reaction, the current, conductance, and capacitance of the device drift considerably with time yielding an aging effect. Further, it is revealed that the dependence of the conductance and capacitance on the aging time stem rapidly from changing time constants of the interface states with aging time. The results are discussed with special reference to well known admittance spectroscopy used for the characterization of interface states.

Admittance of metal–insulator–semiconductor tunnel contacts in the presence of donor–acceptor mixed interface states and interface reaction

Chattopadhyay

2001

Intrinsic Cu gettering at a thermally grown SiO2/Si interface

Bai

Yang

1990

SiO2 film of 1500-Å thickness has been grown by a conventional thermal dry oxidation process on commercial Si(111) and Si(100) wafers. A secondary-ion mass spectrometry study of the SiO2/Si structure showed that a gettering of Cu atoms, which were present in the Si wafers as residual impurities, has occurred at the SiO2/Si interface due to the thermal dry oxidation process. The areal concentration of the Cu atoms at the interface has been found to depend on the Cu concentration in the Si wafers. Areal concentrations in order of 1×1012/cm2 were measured at the interfaces. Facilitated by the high diffusivity of Cu in SiO2 and Si, the gettering is thermodynamically driven by the low solid solubility of Cu, either in SiO2 at the temperature range up to the oxidation temperature, or in Si at low temperatures as the wafers cool down. The defects generated at the SiO2/Si interface provide the nucleation sites for the Cu gettering.

Conductance technique measurements of the density of interface states between ZnS:Mn and p-silicon

Simons

Tayarani‐Najaran

Thomas

1991

Capacitance and conductance measurements are presented for dc-driven Au/ZnS:Mn/p-Si electroluminescence metal-insulator-semiconductor (MIS) devices, where the ZnS:Mn films are deposited by radio frequency sputtering. Stable dc operation is achieved by introducing oxygen into the film during deposition and subsequently annealing. The effect of the post-deposition annealing upon the density of states at the ZnS:Mn/p-Si interface is investigated. As deposited, the devices show unusual MIS C-V characteristics, that indicate a very high interface state density. Annealing at 700 °C, normal C-V characteristics are observed, indicating that the very high density of states is greatly reduced. For these films the conductance technique has been used to measure the density of states at the interface between the ZnS:Mn and p-Si. The statistical model is found to describe most accurately the interface state conductance response. The interface state density consists of a tail of states that varies between 3.7×1013 cm−2 eV−1 at the silicon Fermi level and 1.1×1013 cm−2 eV−1 at the silicon mid-gap. A small peak is superimposed upon this tail at (−0.16±0.01) eV below mid-gap. The tail of states is believed to be intrinsic to the ZnS:Mn/p-Si interface, but evidence suggests that the small peak is due to the presence of oxygen, which is shown by secondary-ion mass spectrometry analysis to accumulate at the interface after annealing at 700 °C. It seems likely that the very high density of interface states in as deposited devices is a consequence of a plasma damage to the silicon surface during growth, creating defects such as silicon dangling bonds. One possible explanation for the decrease in this density is that by annealing at 700 °C, oxygen in the bulk of the film diffuses to the interface, where it mops up these defects by forming compounds such as SiOx. A simpler model of interface recrystallization is also suggested. The doping density in the depletion region of the silicon is calculated as (7.5±0.5)×1014 cm−3, and the interface state capture cross section for holes is found to have mean value of approximately 10−15 cm−2.