Abstract
Interest in the heteroepitaxy of GaAs on Si has never failed in the last years due to the potential for monolithic integration of GaAs-based devices with Si integrated circuits. But in spite of this effort, devices fabricated from them still use homo-epitaxy only. Here we present an epitaxial technique based on the epitaxial lateral overgrowth of micrometer scale GaAs crystals on a thin SiO2 layer from nanoscale Si seeds. This method permits the integration of high quality and defect-free crystalline GaAs on Si substrate and provides active GaAs/Si heterojunctions with efficient carrier transport through the thin SiO2 layer. The nucleation from small width openings avoids the emission of misfit dislocations and the formation of antiphase domains. With this method, we have experimentally demonstrated for the first time a monolithically integrated GaAs/Si diode with high current densities of 10 kA.cm−2 for a forward bias of 3.7 V. This epitaxial technique paves the way to hybrid III–V/Si devices that are free from lattice-matching restrictions, and where silicon not only behaves as a substrate but also as an active medium.
Highlights
The direct epitaxial growth of III–V compounds on Si substrates remains the most desirable approach for III–V/Si hybrid integration
Isolated GaAs microcrystals were grown on (001)Si and (111)Si substrates by the method of Epitaxial Lateral overgrowth on Tunnel Oxide from nano-seed (ELTOn) described in the Methods section of this paper. Their morphology was investigated by transmission electron microscopy (TEM) and their local electrical characterizations were performed by conductive-probe atomic force microscopy (CP-AFM) and Electron Beam Induced Current (EBIC) measurements
According to the diffraction patterns (DPs) taken at different parts of GaAs micro-crystal grown and in the (001)Si substrate we have observed that the micrometer scale GaAs crystal is composed of three differently oriented parts, nominally left, central, and right parts
Summary
The direct epitaxial growth of III–V compounds on Si substrates remains the most desirable approach for III–V/Si hybrid integration. We demonstrate in this paper that the epitaxial lateral overgrowth of GaAs on nano patterned Si substrates with dielectric films appears to be the most promising technique If this technique is coupled with the use of a sufficiently small nucleation area size, it is expected to enable the relaxation of the mismatched material without emission of misfit dislocations. We propose to call this growth method ELTOn for Epitaxial Lateral overgrowth on Tunnel Oxide from nano-seed This integration process presents a promising route to ultrahigh efficiency III–V/Si tandem solar cells with a close to ideal bandgap combination which are free from lattice-matching constraints
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
