Correlative nm-Scale Nonuniformity of Active Charge Carriers and Electrical Potential Along Both the Plane-View and Depth Directions in Group-V-Doped CdTe Thin Films

Chun-Sheng Jiang, John Moseley, Chuanxiao Xiao, Wyatt Metzger, Mowafak Al-Jassim

Research output: Contribution to conferencePaperpeer-review

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 languageAmerican English
Pages1640-1644
Number of pages5
DOIs
StatePublished - 14 Jun 2020
Event47th IEEE Photovoltaic Specialists Conference, PVSC 2020 - Calgary, Canada
Duration: 15 Jun 202021 Aug 2020

Conference

Conference47th IEEE Photovoltaic Specialists Conference, PVSC 2020
Country/TerritoryCanada
CityCalgary
Period15/06/2021/08/20

Bibliographical note

See NREL/CP-5K00-76040 for preprint

NREL 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

Fingerprint

Dive into the research topics of 'Correlative nm-Scale Nonuniformity of Active Charge Carriers and Electrical Potential Along Both the Plane-View and Depth Directions in Group-V-Doped CdTe Thin Films'. Together they form a unique fingerprint.

Cite this