Abstract
We report nanometer-scale imaging on inhomogeneous distributions of active carrier and electrical potential in an As-doped CdTe film along both plane-view and film-depth directions. Despite Se grading, the scanning capacitance microscopy imaging does not show a clear variation of carrier concentration along the depth of the film. Instead, we observe carrier concentration variations of about 1 order of magnitude (high 1015 to low 1017/cm3), with inhomogeneous spatial regions ranging from a few hundred nm to a few \mu \mathrm{m}. This nonuniformity is distributed randomly in both the film lateral and vertical directions, independent of grain structure and grain boundaries (GBs). We further mapped the surface potential using Kelvin probe force microscopy. Higher potential was found on GBs, illustrating positive GB charging but not GB-specific carrier concentration. The results indicate that this suite of techniques can identify nonuniform carrier concentration and potential fluctuations that can contribute to open-circuit voltage deficits in group-V-doped CdTe devices.
Original language | American English |
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Pages | 1640-1644 |
Number of pages | 5 |
DOIs | |
State | Published - 14 Jun 2020 |
Event | 47th IEEE Photovoltaic Specialists Conference, PVSC 2020 - Calgary, Canada Duration: 15 Jun 2020 → 21 Aug 2020 |
Conference
Conference | 47th IEEE Photovoltaic Specialists Conference, PVSC 2020 |
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Country/Territory | Canada |
City | Calgary |
Period | 15/06/20 → 21/08/20 |
Bibliographical note
See NREL/CP-5K00-76040 for preprintNREL Publication Number
- NREL/CP-5K00-79305
Keywords
- CdTe thin-film photovoltaics
- group-V doping
- Kelvin probe force microscopy
- nonuniform doping concentration
- nonuniform electrical potential
- scanning capacitance microscopy