Decrease in gap states at ultrathin SiO2/Si interfaces by crown-ether cyanide treatment

Abstract

A simple method to passivate interface states at ultrathin SiO2/Si interfaces is developed. In this method, ultrathin SiO2-covered Si is immersed in a KCN solution containing crown-ether, followed by a rinse in water at 25 °C. The conductance–voltage measurements show that the interface state density is decreased to ∼1/10 by this crown-ether cyanide treatment. The capacitance–voltage measurements show that contamination by K+ ions is effectively avoided by the inclusion of crown-ether. These results demonstrate that crown-ether molecules effectively capture K+ ions and consequently CN− ions effectively may react with defect states, probably forming Si–CN bonds. The passivation of interface states by the cyanide treatment improves the electrical characteristics of metal–oxide–semiconductor tunneling diodes.

Improvement of Photovoltaic Conversion Efficiency and also Photoluminescence Efficiency of p-Cu2O/n-ZnO thin film heterostructures by Cyanide Treatment

“…That is to say, K + ions do not have direct contact with Cu 2 O, only CN -ions do. Details of the cyanide treatment were described elsewhere [6,7]. The scheme of reaction for the Cyanide treatment are described below.…”

Passivation of a-Si:H-based structures in KCN and HCN solutions and its application on p-i-n solar cell

“…Preparation of intrinsic a-Si:H: device-quality intrinsic a-Si:H layers of the thickness of $0.9 mm (i) or 0.5 mm (ii) were deposited on the n-type Si(100) oriented crystals (phosphorus doped of 0.001-10 V cm conductivity) in a 13.56 MHz rf excited parallel plate plasma enhanced chemical vapor deposition system (1) in laboratories of Princeton University: from pure SiH 4 and its mixture with H 2 at the plasma power of $40 W at the sample temperatures of 250 C; (2) in laboratories of Osaka University: deposition conditions for KCN (HCN) treated samples: SiH 4 -10 sccm, H 2 -90 sccm, 6 W (0.03 Wcm À2 ), 120 Pa, at sample temperature of 160 C.…”

“…The cyanide method can passivate Si surface states, Si/SiO 2 interface states, and defects in amorphous Si -see, e.g. [20][21][22][23].…”

“…There exist different possibilities how to create silicon dioxide layers. It can be done by thermal heating the sample in the oxygen atmosphere, [1,2] by implantation of oxygen atoms by plasma immersion ion implantation (PIII), [3,4] or by etching the surface of the sample by Ar þ ions and thus activated surface exposing to the oxygen atmosphere, [4] etc. All of the above-mentioned techniques belong to gas phase high-or low-pressure techniques.…”

On formation of thin SiO2/a-Si:H interface when biased oxidized semiconductor surface interacts with plasma or liquid solution

“…These include, for example, heating the sample in an oxygen atmosphere [13,14], implantation of oxygen atoms by Plasma Immersion Ion Implantation (PIII) [15,16], or etching the surface of the sample by Ar + ions, thus exposing the activated surface to the oxygen atmosphere [16]. All of these techniques belong to gas-phase, high-or low-pressure techniques.…”