Okamoto Gaku, Kutsuki Katsuhiro, Hosoi Takuji, Shimura Takayoshi, Watanabe Heiji
Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
J Nanosci Nanotechnol. 2011 Apr;11(4):2856-60. doi: 10.1166/jnn.2011.3900.
We have fabricated pure germanium nitrides (Ge3N4) using high-density plasma nitridation and investigated electrical properties of Au/Ge3N4/Ge capacitors. We achieved equivalent oxide thickness (EOT) of 1.4 nm, and dielectric constant of Ge3N4 was estimated to be 9.7. The gate leakage current density of 4.3 A/cm2 in the accumulation condition at V(fb)-1 V, where V(fb) is the flatband voltage, was one order of magnitude lower than that of conventional poly-Si/SiO2/Si stacks. The interface state density (D(it)) of Ge3N4/Ge interfaces evaluated by a low-temperature conductance method exhibited a minimum value of 9.4 x 10(11) cm(-2)eV(-1) at E - E(v) = 0.27 eV. Furthermore, the insulating property and interface quality of Ge3N4/Ge system was found to be thermally stable up to 650 degrees C. These results indicate that Ge3N4 is a promising candidate for either a gate insulator or an interfacial layer under high-k dielectrics for Ge-MIS devices.
我们利用高密度等离子体氮化工艺制备了纯氮化锗（Ge3N4），并研究了Au/Ge3N4/Ge电容器的电学性能。我们实现了1.4纳米的等效氧化层厚度（EOT），估计Ge3N4的介电常数为9.7。在V(fb)-1 V的积累条件下，栅极泄漏电流密度为4.3 A/cm2（其中V(fb)是平带电压），比传统的多晶硅/二氧化硅/硅堆叠低一个数量级。通过低温电导法评估的Ge3N4/Ge界面的界面态密度（D(it)）在E - E(v) = 0.27 eV时表现出最小值9.4 x 10(11) cm(-2)eV(-1)。此外，发现Ge3N4/Ge系统的绝缘性能和界面质量在高达650摄氏度时具有热稳定性。这些结果表明，Ge3N4对于Ge-MIS器件的栅极绝缘体或高k电介质下的界面层来说是一个有前途的候选材料。
