Electrical and optical properties of Ge–implanted 4H–SiC

Abstract

The structural, electronic, and optical properties of single crystalline n-type 4H-SiC implanted with Ge atoms have been investigated through x-ray diffraction ͑XRD͒, Rutherford backscattering spectroscopy ͑RBS͒, Raman spectroscopy, and sheet resistivity measurements. Ge atoms are implanted under the conditions of a 300 keV ion beam energy with a dose of 2ϫ10 16 cm Ϫ2. X-ray diffraction of the Ge-implanted sample showed broadening of the Bragg peaks. A shoulder on the ͑0004͒ reflection indicated an increase in the lattice constant corresponding to substitutional Ge and implantation induced lattice damage, which was repaired through thermal annealing at 1000°C. The diffraction pattern after annealing indicated improved crystal structure and a peak shift to a lower reflection angle of 35.2°. The composition of Ge detected through XRD was reasonably consistent with RBS measurements that indicated 1.2% Ge in a 1600-Å-thick layer near the SiC surface. Raman spectroscopy also showed fundamental differences in the spectra obtained for the Ge-implanted SiC ͑SiC:Ge͒ compared to a pure sample of SiC. Sheet resistivity measurements indicate a higher conductivity in the Ge implant by a factor of 1.94 compared to unimplanted SiC. These results have demonstrated the possibility of substitutional implantation of Ge atoms into the crystalline lattice of 4H-SiC substrates. The change in composition and properties may have numerous electronic device applications including high power, high temperature, optoelectronic, as well as high frequency device structures.

3C‐SiC:Ge alloys grown on Si (111) substrates by SSMBE

“…Additionally, a modification of the band gap is possible. This can be used for band gap engineering applications [2,3]. The disadvantage of this alloy is the predicted thermodynamical metastability of the binary GeC system with respect to decomposition into its elemental constituents (enthalpy of formation of GeC is positive with a value of ∆H = 0.27 eV/atom).…”

“…Therefore nonequilibrium methods of material synthesis must be chosen to form the required composition. Such methods are (1) ion beam synthesis [3,8,9], (2) plasma assisted deposition and (3) MBE at low temperatures [10]. In the present study our effort was to obtain Ge incorporation into the 3C-SiC lattice by using solid source molecular beam epitaxial (SSMBE) growth on Si substrates in order to create a cubic SiC:Ge alloy.…”

A technique to reduce the contact resistance to 4H-silicon carbide using germanium implantation

“…9 The larger atomic size of Ge is expected to increase the lattice constant of SiC for strain compensation or for matching to larger lattice materials, such as GaN. The lattice structure of Ge in SiC was theoretically investigated using an anharmonic Keating model 10 of the atomic potentials to simulate the interatomic spacings.…”

Ge incorporation inside 4H-SiC during homoepitaxial growth by chemical vapor deposition

“…The conditions for the typical CVD growths are 1500°C with 3 µm/h and C/Si = 5 for 1 hour). In the first case, SIMS analysis pointed out that the amount of Ge in the witness layer is less than or equal to the apparatus detection limit which is ~1x10 15 at/cm 3 (figure not shown). In the second case, SIMS analysis showed the presence of Ge in the layer but only located near the epilayer/substrate interface and restricted to several tens of nm only (Fig.…”