Flexible III-V solar cell structure
AssigneeInternational Business Machines Corporation
InventorsStephen W. Bedell, Cheng-Wei Cheng, Bahman Hekmatshoartabari, Ning Li, Devendra K. Sadana, Davood Shahrjerdi
Life of this patent
Estimating the term…
Abstract
Solar cell structures include stacked layers in reverse order on a germanium substrate wherein a n++ (In)GaAs buffer layer plays dual roles as buffer and contact layers in the inverted structures. The absorbing layers employed in such exemplary structures are III-V layers such as (In)GaAs. Controlled spalling may be employed as part of the fabrication process for the solar cell structures, which may be single or multi-junction. The requirement for etching a buffer layer is eliminated, thereby facilitating the manufacturing process of devices using the disclosed structures.
Claims16
A method comprising:
- providing a germanium substrate;
- forming a buffer region directly on the germanium substrate, the buffer region including a highly doped, electrically conductive layer comprising gallium arsenide;
- growing a solar cell structure in inverted order on the buffer region, the solar cell structure including an absorbing layer comprising gallium arsenide, an emitter layer, a window layer adjoining the highly doped, electrically conductive layer, the emitter and window layers being formed between the buffer region and the absorbing layer, and a back surface field layer formed on a side of the absorbing layer opposite from the substrate, the highly doped, electrically conductive layer being functional as a buffer layer between the germanium substrate and the solar cell structure;
- attaching a metal stressor layer to the solar cell structure;
- attaching a flexible handle layer to the metal stressor layer, and
- spalling the solar cell structure under the buffer region, wherein a fracture takes place at or below an interface between the buffer region and germanium substrate using the metal stressor and flexible handle layers.
A method comprising:
- providing a germanium substrate;
- forming a buffer region directly on the germanium substrate, the buffer region including a highly doped, electrically conductive layer comprising a III-V material;
- growing a single- or multi junction solar cell structure including at least one III-V absorbing layer in inverted order on the buffer region such that the highly doped, electrically conductive layer functions as a buffer layer between the germanium substrate and the solar cell structure;
- attaching a metal stressor layer to the solar cell structure;
- attaching a flexible handle layer to the metal stressor layer;
- spalling the solar cell structure under the buffer region, wherein a fracture takes place at or below an interface between the buffer region and germanium substrate using the metal stressor and flexible layers, and,
- if present on the buffer region following spalling, removing a residual germanium layer from the buffer region such that the highly doped, electrically conductive layer is functional as an ohmic contact layer for the solar cell structure upon removal of the residual germanium layer.
Dependencies are inferred from the claim text.