High quality relaxed germanium layers grown on (110) and (111) silicon substrates with reduced stacking fault formation

Abstract

Epitaxial growth of Ge on Si has been investigated in order to produce high quality Ge layers on (110)- and (111)-orientated Si substrates, which are of considerable interest for their predicted superior electronic properties compared to (100) orientation. Using the low temperature/high temperature growth technique in reduced pressure chemical vapour deposition, high quality (111) Ge layers have been demonstrated almost entirely suppressing the formation of stacking faults (< 107 cm−2) with a very low rms roughness of less than 2 nm and a reduction in threading dislocation density (TDD) (∼ 3 × 108 cm−2). The leading factor in improving the buffer quality was use of a thin, partially relaxed Ge seed layer, where the residual compressive strain promotes an intermediate islanding step between the low temperature and high temperature growth phases. (110)-oriented layers were also examined and found to have similar low rms roughness (1.6 nm) and TDD below 108 cm−2, although use of a thin seed layer did not offer the same relative improvement seen for (111).

Characterization of dislocations in germanium layers grown on (011)- and (111)-oriented silicon by coplanar and noncoplanar X-ray diffraction

“…The measured intensity distributions were well described by Gaussians, which enabled us to use a small number of parameters associated with the shape and treat them in a manner similar to the modified Williamson-Hall plot. The misfit dislocations were found to be strongly positionally correlated, and the density of threading dislocations for the Ge/Si(111) layers were in qualitative agreement with TEM observations (Huy Nguyen et al, 2013). corresponds to the interface where misfit dislocations are lying.…”

“…The density of the threading dislocations is underestimated. One of the reasons may be that we did not include the broadening due to the stacking faults (Huy Nguyen et al, 2013). The incorporation of stacking faults into the current formalism will be the topic of future investigations.…”

Experimental Demonstration of Room-Temperature Spin Transport inn-Type Germanium Epilayers

“…However, the 4.2% lattice mismatch between Si and Ge precludes the direct epitaxial growth of high-quality relaxed Ge layers on top of Si wafers. Efforts to overcome this difficulty are still ongoing in Ge-related research [45][46][47][48]. In our study, high-quality Ge channels were successfully grown on top of Si (001) substrates using a two-temperature method.…”

“…The Ge epilayers were grown on standard p − -Sið001Þ substrates using the twotemperature growth method by reduced pressure-chemical vapor deposition [46,48]. The structure consisted of a 1-μm-thick undoped Ge epilayer and a 50 nm heavily n-type doped Ge epilayer with a phosphorous doping concentration of ∼1.0 × 10 19 cm −3 and a degree of relaxation of 104%, calculated from the analysis of measured high-resolution x-ray diffraction symmetrical and asymmetrical reciprocal space maps.…”

Formation of Nanotwin Networks during High-Temperature Crystallization of Amorphous Germanium

“…Indeed, it has been observed that the appearance of twins during epitaxial growth of Si wafers resulted in faulty devices, while for other defects, such as e.g. extrinsic stacking faults, it did not 44 45 46 (albeit perfect Ge crystals have been grown in the [111] direction as well 33 ). This may be of importance in GST materials where high contrast between amorphous and crystalline phases in terms of these properties is desired.…”