Microelectronic Structure and Doping Nonuniformity of Phosphorus-Doped CdSeTe Solar Cells

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Advancing cadmium telluride (CdTe) photovoltaic technology relies on optimizing group-V doping and selenium alloying.
• Understanding microelectronic structures is crucial for improving device performance.

Purpose of the Study:

• To characterize nanometer-scale microelectronic structures in phosphorus (P)-doped CdSeTe photovoltaic devices.
• To correlate doping non-uniformities with potential distribution for device optimization.

Main Methods:

• Utilized Kelvin probe force microscopy (KPFM) to image potential drop distribution across device cross-sections.
• Employed scanning spreading resistance microscopy (SSRM) on delaminated interfaces and beveled bulk to reveal doping polarity and carrier concentration.
• Corroborated KPFM and SSRM findings to link non-uniform doping with potential features.

Main Results:

• Non-uniform doping, revealed by SSRM, corresponds to non-uniform potential observed by KPFM.
• Enhancing P-doping mitigated detrimental microelectronic structures, reducing potential drop and n-p transition depth.
• High-level P-doping significantly reduced interface potential irregularities and favored p-type doping.

Conclusions:

• Characterization reveals complex defect chemistry and electronic structures in Se-alloyed CdTe with group-V doping.
• Mitigating non-uniform doping and irregular potentials is key to enhancing CdTe photovoltaic device efficiency.