Abstract
We demonstrate the feasibility of growing GaAs nanomembranes on a plastically-relaxed Ge layer deposited on Si (111) by exploiting selective area epitaxy in MBE. Our results are compared to the case of the GaAs homoepitaxy to highlight the criticalities arising by switching to heteroepitaxy. We found that the nanomembranes evolution strongly depends on the chosen growth parameters as well as mask pattern. The selectivity of III-V material with respect to the SiO2 mask can be obtained when the lifetime of Ga adatoms on SiO2 is reduced, so that the diffusion length of adsorbed Ga is high enough to drive the Ga adatoms towards the etched slits. The best condition for a heteroepitaxial selective area epitaxy is obtained using a growth rate equal to 0.3 ML/s of GaAs, with a As BEP pressure of about 2.5 × 10−6 torr and a temperature of 600 °C.
Highlights
In the quest for advanced opto-electronic materials, the integration of III–V semiconductor devices with silicon technology is one of the most topical challenges
We focus on the achievement of 3D GaAs nanomembranes of regular morphology integrated on a Si wafer
We describe how a suitable tuning of the growth conditions permits achieving well-faceted morphologies consistent with the homoepitaxial one, offering a first proof-of-concept of the integration of GaAs nanomembranes on Ge/Si substrates by selective area growth
Summary
In the quest for advanced opto-electronic materials, the integration of III–V semiconductor devices with silicon technology is one of the most topical challenges. Selective area epitaxy (SAE) approach can be exploited to grow three-dimensional (3D) GaAs nano-structures, not achievable by direct deposition onto a bare substrate [11,12]. We focus on the achievement of 3D GaAs nanomembranes of regular morphology integrated on a Si wafer. To such a goal, a Ge virtual substrate is exploited by depositing. [18] to assess the impact of using the Ge virtual substrate on the selective growth of GaAs. Here, we describe how a suitable tuning of the growth conditions permits achieving well-faceted morphologies consistent with the homoepitaxial one, offering a first proof-of-concept of the integration of GaAs nanomembranes on Ge/Si substrates by selective area growth
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