Alta Devices, Inc.

Thomas J Gmitter

Gang He

Melissa J Archer

Andreas G Hegedus

Gregg Higashi

Harry A Atwater

Isik C Kizilyalli

Brian J Brown

Brian Hayes Burrows

Stewart Sonnenfeldt

Siew Neo

David Berkstressor

Brendan M Kayes

Methods and apparatus for converting electromagnetic radiation, such as solar energy, into electric energy with increased efficiency when compared to conventional solar cells are provided. A photovoltaic (PV) device generally includes a window layer; an absorber layer disposed below the window layer such that electrons are generated when photons travel through the window layer and are absorbed by the absorber layer; and a plurality of contacts for external connection coupled to the absorber layer, such that all of the contacts for external connection are disposed below the absorber layer and do not block any of the photons from reaching the absorber layer through the window layer. Locating all the contacts on the back side of the PV device avoids solar shadows caused by front side contacts, typically found in conventional solar cells. Therefore, PV devices described herein with back side contacts may allow for increased efficiency when compared to conventional solar cells.

Photovoltaic device with back side contacts

An optoelectronic device and a method for fabricating the optoelectronic device are disclosed. The optoelectronic device comprises a p-n structure, a patterned dielectric layer comprising a dielectric material and a metal layer disposed on the dielectric layer. The metal layer makes one or more contact to the p-n structure through the patterned dielectric layer. The dielectric material may be chemically resistant to acids and may provide adhesion to the p-n structure and the metal layer. The method for fabricating an optoelectronic device comprises providing a p-n structure, providing a dielectric layer on the p-n structure and providing a metal layer on the dielectric layer and then lifting the device off the substrate, such that after the lift off the p-n structure is closer than the patterned dielectric layer to a front side of the device; wherein the device comprises the p-n structure, the patterned dielectric layer, and the metal layer.

Optoelectronic device with dielectric layer and method of manufacture

Methods and apparatus are provided for converting electromagnetic radiation, such as solar energy, into electric energy with increased efficiency when compared to conventional solar cells. One embodiment of the present invention provides a photovoltaic (PV) device. The PV device comprises an absorber layer made of a compound semiconductor; and an emitter layer located closer than the absorber layer to a first side of the device. The PV device includes a p-n junction formed between the emitter layer and the absorber layer, the p-n junction causing a voltage to be generated in the device in response to the device being exposed to light at a second side of the device. Such innovations may allow for greater efficiency and flexibility in PV devices when compared to conventional solar cells.

Photovoltaic device

Embodiments described herein provide processes for forming and removing epitaxial films and materials from growth wafers by epitaxial lift off (ELO) processes. In some embodiments, the growth wafer has edge surfaces with an off-axis orientation which is utilized during the ELO process. The off-axis orientation of the edge surface provides an additional variable for controlling the etch rate during the ELO process and therefore the etch front may be modulated to prevent the formation of high stress points which reduces or prevents stressing and cracking the epitaxial film stack. In one embodiment, the growth wafer is rectangular and has an edge surface with an off-axis orientation rotated by an angle greater than 0&#xb0; and up to 90&#xb0; relative to an edge orientation of &#x3c;110&#x3e; at 0&#xb0;.

Off-axis epitaxial lift off process

Epitaxial lift off systems and methods are presented. In one embodiment a tape is disposed on the opposite side of the epitaxial material than the substrate is used to hold the epitaxial material during the etching and removal steps of the ELO process. In various embodiments, the apparatus for removing the ELO film from the substrates without damaging the ELO film may include an etchant reservoir, substrate handling and tape handling mechanisms, including mechanisms to manipulate (e.g., cause tension, peel, widen the etch gap, etc.) the lift off component during the lift off process.

Epitaxial lift off systems and methods

Embodiments of the invention generally relate to apparatuses and methods for producing epitaxial thin films and devices by epitaxial lift off (ELO) processes. In one embodiment, a method for forming thin film devices during an ELO process is provided which includes coupling a plurality of substrates to an elongated support tape, wherein each substrate contains an epitaxial film disposed over a sacrificial layer disposed over a wafer, exposing the substrates to an etchant during an etching process while moving the elongated support tape, and etching the sacrificial layers and peeling the epitaxial films from the wafers while moving the elongated support tape. Embodiments also include several apparatuses, continuous-type as well as a batch-type apparatuses, for forming the epitaxial thin films and devices, including an apparatus for removing the support tape and epitaxial films from the wafers on which the epitaxial films were grown.

Tape-based epitaxial lift off apparatuses and methods

Embodiments described herein provide processes for forming and removing epitaxial films and materials from growth wafers by epitaxial lift off (ELO) processes. In some embodiments, the growth wafer has edge surfaces with an off-axis orientation which is utilized during the ELO process. The off-axis orientation of the edge surface provides an additional variable for controlling the etch rate during the ELO process- and therefore the etch front may be modulated to prevent the formation of high stress points which reduces or prevents stressing and cracking the epitaxial film stack. In one embodiment, the growth wafer is rectangular and has an edge surface with an off-axis orientation rotated by an angle greater than 0&#xb0; and up to 90&#xb0; relative to an edge orientation of &#x3c;110&#x3e; at 0&#xb0;.

Embodiments of the invention generally relate to epitaxial lift off (ELO) thin films and devices and methods used to form such films and devices. In one embodiment, a method for forming an ELO thin film is provided which includes depositing an epitaxial material over a sacrificial layer on a substrate, adhering a flattened, pre-curved support handle onto the epitaxial material, and removing the sacrificial layer during an etching process. The etching process includes bending the pre-curved support handle to have substantial curvature while peeling the epitaxial material from the substrate and forming an etch crevice therebetween. Compression is maintained within the epitaxial material during the etching process. The flattened, pre-curved support handle may be formed by flattening a pre-curved support material.

Epitaxial lift off stack having a pre-curved handle and methods thereof

An apparatus or method for forming a tape-based, epitaxial lift-off film. The epitaxial lift-off film can be for at least one of a solar device, a semiconductor device, and an electronic device. The apparatus can comprise: a tape supply section, the tape supply section providing an unloaded support tape; a lamination section for receiving the unloaded support tape and a plurality of substrates, each substrate containing an epitaxial film thereon, the lamination section adhering the substrates to the unloaded support tape to form a loaded support tape; and an ELO etch section comprising a pressure system for applying pressure on said loaded support tape such that pressure is applied progressively downward and progressively towards a center-line of said loaded support tape when passing through said ELO etch section, the ELO etch section removing the substrates from the loaded support tape, while leaving the epitaxial film on the loaded support tape.

An apparatus, system and method for performing ELO are disclosed. Device assemblies are contemporaneously etched in a stacked arrangement. Each device assembly may be placed in a respective tray, where the trays are overlapped and spaced apart from one another. In this manner, more device assemblies can be etched per unit area compared to conventional systems. Further, by stacking device assemblies during etching, the yield can be improved and/or the cost of the etch tank and associated hardware can be reduced.

System and method for improved epitaxial lift off

Methods and apparatus are provided for converting electromagnetic radiation, such as solar energy, into electric energy with increased efficiency when compared to conventional solar cells. A photovoltaic (PV) unit may have all electrical contacts positioned on the back side of the PV device to avoid shadowing and increase absorption of the photons impinging on the front side of the PV unit. Several PV units may be combined into PV banks, and an array of PV banks may be connected to form a PV module with thin strips of metal or conductive polymer formed at low temperature. Such innovations may allow for greater efficiency and flexibility in PV devices when compared to conventional solar cells.

Growing community of inventors

Sunnyvale, CA, United States of America

Thomas J Gmitter