Control of electrical properties in Heusler-alloy/Ge Schottky tunnel contacts by using phosphorous δ-doping with Si-layer insertion

We experimentally demonstrate the control of electrical properties of Heusler-alloy/Ge contacts by phosphorous (P) δ-doping techniques with Si-layer insertion. Low-temperature molecular beam epitaxy methods enable us to obtain the high quality Heusler-alloy/Ge heterointerfaces with P δ-doped layers. Although the resistance area product (RA) values are scattered in the Heusler-alloy/Ge interfaces with conventional δ-doping techniques, we precisely adjust the RA values in the newly developed interface with Si-layer insertion. This method will open a way for developing source and drain structures in Ge-based spintronics devices.