A combined chemical vapor deposition and rapid thermal diffusion process for SiGe Esaki diodes by ultra-shallow junction formation

SiGe Esaki diodes have been realized by rapid thermal diffusion of phosphorous into an SiGe layer grown by ultra-high-vacuum chemical-vapor-deposition on an Si p⁺-substrate for the first time. The phosphorous-doped SiGe forms the n⁺-electrode, while heavily boron-doped Si_0.74Ge_0.26 and Si substrate is used for the p⁺ electrode. The diodes show a peak current density of 0.18 kA/cm², a current peak-to-valley ratio of 2.6 at room temperature, and they exhibit only a weak temperature dependence. Cross-sectional transmission microscopy showed a good crystalline quality of the strained Si_0.74Ge_0.26 layer even after the diffusion step at 900°C.