a-Ge:H薄膜の水素結合モードと欠陥補償

概要

論文の詳細を見る
Hydrogenated amorphous Ge (a-Ge : H) thin films were prepared by the capacitively-coupled plasma CVD method using GeH_4 as a reactive gas. The films, which involved only monohydride bonding and which involved mainly dihydride bonding, were deposited by changing the deposition conditions such as deposition temperature, concentration of GeH_4 in H_2 gas, gas flow rate, and rf power density. Infrared absorption spectra, temperature dependence of dark- and photo-conductivity of the films were measured to examine the defect-compensation-effect due to the different hydrogen bonding modes. It was confirmed from IR measurement that the IR absorption spectra were nearly consistent with the curves of Gaussian distribution function. With this result the complicated spectra were divided into three absorption peaks. Although any impurity atoms were not doped in a-Ge : H films, both n- and p-type films were deposited, depending on the deposition conditions. That is, the film which contained only monohydride bonding was n-type, while the films containing mostly dihydride bonding were p-type. The optical energy gap of both types of a-Ge : H was 1.0 eV. The Fermi level of the film with only monohydride bonding lay 0.35 eV below the conduction band, and that of the film with mostly dihydride donding lay 0.40 eV above the valence band. The band tail widths near the conduction band of the n- and p-type films were 0.15 eV and 0.10 eV, respectively. From these results, it was concluded that the monohydride-bonding hydrogen atoms terminated the gap states mainly below midgap, and the dihydride-bonding hydrogen atoms chiefly decreased the gap states above midgap.
東海大学の論文

a-Ge:H薄膜の水素結合モードと欠陥補償

スポンサーリンク

概要

著者

関連論文

スポンサーリンク