Development and Fabrication of High Efficiency N-Type Selective Emitter Silicon Solar Cells with APCVD Boron Emitter

Committee: 

Dr. Rohatgi, Advisor     

Dr. Gaylord, Chair

Dr. Correa-Baena

Abstract:

The objective of the proposed research is to fabricate high efficiency n-type silicon solar cells with a selective emitter using atmospheric pressure chemical vapor deposition (APCVD). N-type silicon is an emerging technology in industry due to its potential for higher efficiency than p-type without suffering from the same defects and metal impurities. Since efficiency reduces the cost of each link in the PV value chain, the proposed objective will have a significant impact on the overall LCOE that enables solar technology to reach grid parity with conventional fossil fuels. This will be accomplished through fundamental understanding, materials growth and characterization, and technology innovations. High efficiency large area cells will be fabricated to demonstrate the commercial readiness of these advanced cells with a goal of > 22.5%. In order to reach that target, a key component of the cell is the reduction of saturation current density (Jo), which leads to higher voltage, and thus efficiency. This proposal will focus on several topics: (1) achieving a very low Joe by investigating the viability of APCVD boron emitters compared to a more conventional ion implanted emitter, (2) studying the passivation of boron diffused emitters with aluminum oxide (Al2O3) and its impact on Joe, (3) developing a novel selective boron emitter (p++-p+) to decouple the heavily defused areas under the metal contacts from the lightly doped areas in the field passivated regions to reduce metal-induced recombination and total Joe, and (4) investigating and fabricating advanced cell structures to take full advantage of the benefit gained from selective emitter towards the goal of achieving > 22.5% efficient cells.