Ge/Si异质键合技术作为一种新型的通用材料制备工艺,在制备高质量Si基Ge薄膜方面展现出巨大的潜力,是研制高性能Ge/Si光电器件的备选方案之一。现阶段主流的直接键合和等离子体键合方法在制备Ge/Si薄膜时都容易在Ge/Si键合界面处引入纳米氧化锗层(GeO2),导致Ge/GeO2及GeO2/Si半/绝接触界面存在界面态,从而器件性能受影响。基于载流子三大输运方程、非局域隧穿模型及半经典量子解法,构建了低温Ge/Si异质键合界面,研究了键合界面的界面态密度(ISD)对Ge/Si异质结的载流子电学输运、光吸收、复合及高频响应等性能的影响。结果表明,随着ISD的增加,Ge/Si异质结的暗电流增大,同时界面态对载流子的俘获能力加强,导致总电流减小,光谱响应减弱。另外,ISD的增加导致Ge层内的电场减小,高频特性变差。为获得性能良好的键合Ge/Si异质结,ISD必须低于1×10 12 cm -2。该研究结果为高质量Si基Ge薄膜及高性能Ge/Si光电器件的制备提供了理论指导。

As a new common material fabrication technique, Ge/Si heterogeneous wafer bonding exhibits enormous potentials in the fabrication of high-quality Si-based Ge films. It is also regarded as an alternative solution for the fabrication of high-performance Ge/Si photoelectric devices. However, there easily exists a nanometer GeO₂ oxide layer at the Ge/Si bonded interface fabricated by the direct bonding or plasma bonding method. This leads to the formation of an interface state at the Ge/GeO₂ and GeO₂/Si semiconductor-insulator contact layer, which in turn affects the performance of the device. A low-temperature Ge/Si bonded interface is constructed based on the three carrier transport equations, the non-local tunneling model, and the semi-classical quantum solution. The effect of the interface state density (ISD) on the carrier electrical transport, light absorption, recombination, and high-frequency response is studied. The results show that with the increase of ISD, the dark current of the Ge/Si heterojunction increases. At the same time, the carrier capture effect becomes more obvious, leading to the decrease in the total current and the spectral response. In addition, the increase of ISD leads to the worsening frequency response and the decrease in the electric field within the Ge layer. Moreover, the ISD must be smaller than 1×10 ¹² cm ^-2 to obtain a high-performance Ge/Si bonded heterojunction. These results may give a theoretical guidance for the fabrication of high-quality Si-based Ge films and high-performance Ge/Si photoelectric devices.