Sunpower Corporation

Peter Cousins

Denis De Ceuster

Thomas Pass

Richard M Swanson

Jane Manning

Hsin-Chiao Luan

John Ferrer

Rex Gallardo

Stephen F Meyer

A system for substrate deposition. The system includes a wafer pallet and an anode. The wafer pallet has a bottom and a top. The top of the wafer pallet is configured to hold a substrate wafer. The anode has a substantially fixed position relative to the wafer pallet and is configured to move with the wafer pallet through the deposition chamber. The anode is electrically isolated from the substrate wafer.

Deposition system with electrically isolated pallet and anode assemblies

In one embodiment, a solar cell has base and emitter diffusion regions formed on the back side. The emitter diffusion region is configured to collect minority charge carriers in the solar cell, while the base diffusion region is configured to collect majority charge carriers. The emitter diffusion region may be a continuous region separating the base diffusion regions. Each of the base diffusion regions may have a reduced area to decrease minority charge carrier recombination losses without substantially increasing series resistance losses due to lateral flow of majority charge carriers. Each of the base diffusion regions may have a dot shape, for example.

Solar cell with reduced base diffusion area

In one embodiment, active diffusion junctions of a solar cell are formed by diffusing dopants from dopant sources selectively deposited on the back side of a wafer. The dopant sources may be selectively deposited using a printing method, for example. Multiple dopant sources may be employed to form active diffusion regions of varying doping levels. For example, three or four active diffusion regions may be fabricated to optimize the silicon/dielectric, silicon/metal, or both interfaces of a solar cell. The front side of the wafer may be textured prior to forming the dopant sources using a texturing process that minimizes removal of wafer material. Openings to allow metal gridlines to be connected to the active diffusion junctions may be formed using a self-aligned contact opening etch process to minimize the effects of misalignments.

Back side contact solar cell structures and fabrication processes

A silicon solar cell has doped amorphous silicon contacts formed on a tunnel silicon oxide layer on a surface of a silicon substrate. High temperature processing is unnecessary in fabricating the solar cell.

Solar cell having doped semiconductor heterojunction contacts

A solar cell having backside contacts is economically fabricated through use of acceptor and donor polymers which are inkjet printed in interleaved patterns on the back surface as the carrier accepting electrodes of the solar cell. The polymers can be placed on a tunnel oxide on the surface of a semiconductor substrate, or the polymers can be in direct contact with the semiconductor substrate. Electrical patterns interconnecting the acceptor and donor polymer patterns can also be formed by inkjet printing a seed layer and then electroplating the seed layer. Advantageously, high temperature processing is not required in the process as is required in conventional solar cell fabrication using dopant implants into the semiconductor substrate. In alternative embodiments, doped contacts are diffused in the top surface and a polymer contact is formed over the back surface.

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Muntinlupa, Philippines

Peter Cousins