Realization and characterization of thin single crystal Ge films on sapphire

Abstract

We have successfully produced and characterized thin single crystal Ge films on sapphire substrates (GeOS). Such a GeOS template offers a cost-effective alternative to bulk germanium substrates for applications where only a thin (<2 μm) Ge layer is needed for device operation. The GeOS templates have been realized using the Smart Cut TM technique. 100 mm diameter GeOS templates have been manufactured and characterized to compare the Ge thin film properties with bulk Ge. Surface defect inspection, SEM, AFM, defect etching, XRD and Raman spectroscopy were all performed. The results obtained for each characterization technique used have highlighted that the material properties of the transferred thin Ge film were very close to the ones of a bulk Ge reference. An epitaxial AlGaInP/GaInP/AlGaInP double heterostructure was grown atop the GeOS template to demonstrate the template's stability under the conditions encountered in typical device realization. The photoluminescent behavior of this epitaxial structure was nearly identical to that of a similar structure grown on a bulk Ge substrate. The GeOS templates therefore offer a viable alternative to bulk Ge substrates in the fabrication of devices whose operation is compatible with a thin film structure.

InP-based composite substrates for four junction concentrator solar cells

“…All the transferred layers were found to be fully relaxed, with lattice parameters very close to the bulk InP reference: the residual deformation in the transferred InP layers is in the 0 -0.004% range. It is known that the implantation step involved in the Smart Cut TM technology leads to XRD spectra with strong peak offsets, due to the presence of hydrogen-related defects [7]. Here the finishing steps developed specifically for the InP transferred layers have permitted to totally heal those residual defects and restore a crystalline quality similar to that of bulk InP.…”

Heteroepitaxy of High-Mobility Germanium on Sapphire (0001) with Magnetron Sputtering

“…Examples include infrared photovoltaic devices, mixed-signal complementary metal–oxide–semiconductor (CMOS) devices, and radio frequency (rf) circuit and devices . Compared to the expensive bulk single-crystal germanium substrate, thin-film germanium on insulator (GOI) offers a more cost-efficient solution owing to its capability of growing only a thin layer of germanium film with a thickness of several micrometers or less, which is essential for those applications. The underlying insulator substrates offer numerous advantages, such as reduced parasitic capacitance and power dissipation, increased transistor switching speed, and higher packing density .…”

“…Among insulator materials, sapphire stands out as an excellent candidate for GOI applications. As a commercially available “front-end” material, it is transparent to visible light and demonstrates less thermal expansion coefficient mismatch to germanium . It offers high resistivity, lower rf losses, and superior crosstalk suppression compared to silicon-based insulators …”

Opto-electronic characterizations of oriented nano-structure CdSe film/Si (001) heterostructure

“…Si is initially considered as a unique substrate for the availability of high-quality large bulk single crystals. Another advantage of Si relative to other materials is its low price, placing it as a high potential candidate for industrial applications [11,12]. The substrate thickness should be larger enough compared to the film thickness to offer adequate mechanical strength for practical device processing, while remaining thin enough to avoid wasting expensive material [12].…”

“…As recognized long ago [13], (0 0 1)-oriented Si substrates reduced the formation of antiphase domains and stacking faults at the epitaxial layer and Si misfit interfaces. However, the presence of a high density of structural defects associated with the large differences in lattice constants and thermal expansion coefficients between epitaxial layer and Si exhibiting extremely short lifetime and poor characteristics of the resulting devices [12][13][14][15][16]. In addition, as the continuing miniaturization of the advanced semiconductor devices is going into nano world, this obviously will enhance the influence of lattice defects on their optoelectronic properties of the devices.…”