Self-Aligned PV Contact via Dielectric Breakdown
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Solution Overview
Problem
The alignment and electrical properties of contacts on typical photovoltaic (PV) cells with large area p-n-junctions in doped silicon need improvement to enhance efficiency, as current methods do not effectively reduce electrical resistance and maintain passivation properties.
Innovation Solution
A method involving a substrate with differently doped regions, a passivation layer, and a conductive layer where an electric field is applied to induce localized dielectric breakdown, forming self-aligned electrical contacts without affecting adjacent regions' passivation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If contacts are formed by penetrating through the passivation layer to contact highly doped regions, then electrical contact is achieved, but alignment precision and electrical properties need improvement
Solution Approach 1:
The method employs self-aligned contact formation where the high doping concentration regions automatically define the contact locations through localized dielectric breakdown. The breakdown occurs precisely at the doped regions due to their different electrical properties, eliminating the need for separate alignment steps and achieving both high precision and reliability simultaneously
Solution Approach 2:
The invention utilizes changes in doping concentration parameters to create distinct electrical zones. By forming high doping concentration regions (1e18 to 1e21 atoms/cm³) within the substrate, the method creates localized areas with different breakdown voltages, enabling precise contact formation through electric field application without compromising alignment precision
2Reliability
If dielectric breakdown is induced to reduce electrical resistance, then contact resistance is reduced, but passivation properties of adjacent regions must be maintained
Solution Approach 1:
The method applies localized dielectric breakdown only at the high doping concentration regions where contacts are needed. The electric field is concentrated at these specific locations due to their different electrical properties, causing breakdown only where required while leaving the passivation layer intact in adjacent low-doping regions, thus maintaining passivation properties where needed
Solution Approach 2:
The substrate is segmented into distinct high doping concentration regions and low doping concentration regions. This segmentation allows the dielectric breakdown process to be spatially separated, affecting only the high-doping regions for contact formation while preserving the passivation layer in other areas, resolving the contradiction between contact reliability and passivation maintenance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method reduces electrical resistance at specific regions, forms self-aligned contacts, and maintains passivation properties, improving PV cell efficiency by reducing recombination of charge carriers at the rear surface.
Implementation Method 1
applying an electric field between the at least one first region and the conductive layer in a manner such that locally a dielectric breakdown of the sandwiched passivation layer material is induced
Implementation Method 2
forming the at least one first region may comprise thermal diffusion
Implementation Method 3
forming the at least one first region comprises laser doping
Data Source
AI summary
The present disclosure provides a method of forming a contact for a photovoltaic (PV) cell. The method comprises the step of providing a substrate of a semiconductor material. The substrate has first regions that have a first doping property and are located at first surface portions. The method also comprises depositing a passivation layer on the surface of the substrate including the first surface portions. Further, the method comprises depositing a conductive layer on the passivation layer such that material of the passivation layer is sandwiched between the first regions and the conductive layer. In addition, the method comprises applying an electric field between the first regions and the conductive layer in a manner such that locally a dielectric breakdown of the sandwiched passivation layer material is induced. The first regions having a doping property and the method is conducted such that an electrical resistance is reduced in the passivation layer at the first regions and an electrical contact is formed.