Wafer bonded epitaxial templates for silicon heterostructures

Abstract

A heterostructure device layer is epitaxially grown on a virtual substrate, such as an InP / InGaAs / InP double heterostructure. A device substrate and a handle substrate form the virtual substrate. The device substrate is bonded to the handle substrate and is composed of a material suitable for fabrication of optoelectronic devices. The handle substrate is composed of a material suitable for providing mechanical support. The mechanical strength of the device and handle substrates is improved and the device substrate is thinned to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. An upper portion of the device film exfoliated from the device substrate is removed to provide a smoother and less defect prone surface for an optoelectronic device. A heterostructure is epitaxially grown on the smoothed surface in which an optoelectronic device may be fabricated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the field of semiconductor processing of films and in particular to processing nonsilicon films on heterostructures. 2. Description of the Prior Art The optoelectronics, photovoltaics, telecommunications, and LED industries have a need for a substrate technology that allows them to use a low-cost readily available substrate like Si as a mechanical support for a thin film of optoelectronic material on which to fabricate a device. Some obvious advantages are improved mechanical strength and superior thermal conductivity relative to a bulk optoelectronic material. Group III-V semiconductor layered structures grown on bulk germanium substrates have been used in the prior art to create high efficiency triple-junction solar cells with efficiencies greater than 30%. However, these are prohibitively expensive for all but space applications, because the Ge substrate constitutes a large portion of this cost. ...

AI Technical Summary

Benefits of technology

The invention is an improvement in a method of epitaxially growing heterostructures on a virtual substrate comprised of an optoelectronic device substrate and handle substrate. The method comprises the step of initiating bonding of the device substrate to the handle substrate. The device substrate is composed of a material suitable for fabrication of optoelectronic devices therein and the handle substrate is composed of an inexpensive material suitable for providing mechanical support. The mechanical strength of the device and handle substrates is improved. The device substrate is thinned to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. An upper portion of the device film exfoliated from the device substrate is removed to provide a smoother and less defect prone surface for subsequent optoelectronic device fabrication. The heterostructure is epitaxially grown on the smoothed surface.

The invention is also defined as an improvement in a heterostructure device layer which is epitaxially grown on a virtual substrate. The improvement comprises a device substrate and a handle substrate from which the virtual substrate is formed. The device substrate is bonded to the handle substrate and is composed of a material suitable for fabrication of optoelectronic devices. The handle substrate is composed of a material suitable for providing mechanical support. The mechanical strength of the device and handle substrates is improved and the device substrate is thinned to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. An upper portion of the device film exfoliated from the device substrate is removed to provide a smoother and less defect prone surface for an optoelectronic device. A heterostructure is epitaxially grown on the smoothed surface in which an optoelectronic device may be fabricated.

Problems solved by technology

However, these are prohibitively expensive for all but space applications, because the Ge substrate constitutes a large portion of this cost.

Images