Impact of silicon substrate germanium doping on diode characteristics and on thermal donor formation

Ge-doped Si is of potential interest for specific microelectronics applications; in particular, it is known that its incorporation can lead to an improvement of the radiation hardness of the Si. However, the role of the introduced Ge in the electrical stability of the material is also of special concern. In this contribution we investigate the effects of thermal anneals on the electrical characteristics of p-on-n diodes fabricated on Czochralski-grown Ge-doped-Si and on control Si wafers. Diodes fabricated on high resistivity (HR) magnetic CZ, as well as standard HR float zone (FZ) and oxygenated FZ are also added for comparison. The results show little differences between the electrical characteristics of the devices fabricated on the CZ Si and CZ SiGe substrates; however, the differences increase after thermal anneals. Interestingly and important for device applications, less thermal donor generation is found for the case of the Ge-doped material. The obtained results should be taken into account when defining potential applications of Ge-doped materials.