In situ doped phosphorus diffusion behavior in germanium epilayer on silicon substrate by ultra-high vacuum chemical vapor deposition

Abstract

Phosphorus diffusion behaviors in in situ doped germanium epilayers on Si substrate grown in an ultra high vacuum chemical vapor deposition system at 500 °C are investigated. The phosphorus diffusion mechanism during the growth process is dominated by the extrinsic diffusion process, which can be well described with a model including a cubic dependence of diffusivity on the doping concentration. The phosphorus diffusivity into the boron-doped Ge is lower than that into the intrinsic Ge layer by about one order of magnitude. An in situ doped Ge n/p junction with rectification ratio of 1.84 × 102 is achieved by inserting an intrinsic Ge layer to avoid impurity compensation.

Germanium n+/p Shallow Junction With Record Rectification Ratio Formed by Low-Temperature Preannealing and Excimer Laser Annealing

“…For the sample annealed at 150 mJ/cm 2 with preannealing, the junction depth is only about 44 nm at the concentration of 1 × 10 18 cm −3 , which is just the same as that in the as-implanted sample. The slight diffusion only occurs in the region with phosphorus concentration above 1 × 10 18 cm −3 , and the diffusivity seems to depend on the dopant concentration, as reported in [7] and [8]. It results in a sharper boxshaped shallow junction.…”

“…It has been demonstrated that most n-type dopants diffuse in Ge via vacancy-mediated mechanisms [7], [8]. It was reported that phosphorus diffusivities calculated from dopant profiles produced after rapid thermal annealing were much higher than those after a long-time annealing at the same temperatures [9].…”

Properties of n-Ge epilayer on Si substrate within-situdoping technology

“…More details of the growth conditions can be found elsewhere. [17,18] The doping concentrations of the samples are estimated by the four-point probe method and confirmed by secondary ion mass spectrometry (SIMS). The surface morphologies of the samples are analyzed by atomic force microscopy (AFM) in a tapping mode.…”

Defect engineering for shallow n‐type junctions in germanium: Facts and fiction

“…. A technique gaining more and more popularity is in situ doping during CVD of epitaxial Ge layers, using PH 3 as a dopant precursor . This allows the fabrication of steep profiles, with little diffusion since typical CVD temperatures are in the range of 350–400 °C.…”