Germanium as a versatile material for low-temperature micromachining

Micro and nanofabrication of SiGe/Ge bridges and membranes by wet-anisotropic etching

“…For this reason they have been widely used in order to create suspended structures, for example by an etch against the etch-resistive {1 1 1} planes in Si(0 0 1) substrates [16,17] or by exploiting the underetching rates of a Si(0 0 1) substrate [18,19]. Germanium is extremely chemically resistive against KOH or TMAH [20,21], so it is potentially an excellent material for this kind of micromachining. Therefore, in this work a combination of lithographic process and dry and wet anisotropic etching has been used for the fabrication of both bridge and membranes which could be used to obtain a tensile strained material by a subsequent lithographic processes.…”

Direct Bonding of Ge-Ge Using Epitaxially Grown Ge-on-Si Wafers

“…dust, moisture, particles) during processing at the wafer level. Ge has been reported to be impervious 16 to potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH), and buffered oxide etch (BOE). The relatively low etch rate in these etching solutions make Ge an ideal masking or etch stop layer for Si structures.…”

“…On the contrary, Ge can be used as sacrificial layer with typical wet etchants such as HNO 3 /H 2 O/HCl, HCl/H 2 O 2 and RCA SC-1 cleaning solution since these mixtures have low etch rate on Si, SiO 2 and SiN. 16 For example, dilute H 2 O 2 can be used as a release agent for Ge and this approach has the advantage that no additional protective layer is required to protect the underlying structures. With the wide-spread integration of Ge into Si processing, study on the bonding behavior of Ge-Ge can potentially useful for application listed above.…”

Low temperature silicon-based epitaxy for solar cells applications

“…(ii) Ge has ~4 times better electron and hole mobility as compared to Si; [51] (iii) Ge can be a good etch stop candidate during Si emitter texturization as it is resistant to etchants such as tetramethylammonium hydroxide (TMAH) and potassium hydroxide (KOH); [52] (iv) Ge has exhibited good properties as the bottom junction material in tandem solar cell. [53] Chapter 4 Low Temperature Back Germanium Epitaxy on Epitaxial Emitter Silicon Solar Cells (highly doped substrate) However, the above approach did not include the challenges related to large-scale manufacturing and the PCE degradation caused by the defective Si/Ge heterointerface, with the latter being more critical.…”