Recently, the demand for non-destructive contact-free measurement tools which are able to measure conductivity distributions independent of surface morphology at spatial resolutions down to a few micrometres has strongly increased. This demand is caused by an increased application of micron-scale doping areas in solar cells (e.g. selective emitter structures or interdigitated back-contact (IBC) cells) and further semiconductor applications. In this work a recently introduced method based on the photoconductive (PC) near-field detection of terahertz (THz) light transmission is introduced for sheet resistance imaging on rough laser-doped multi-crystalline (mc) silicon samples featuring doping microstructures. Furthermore spatially resolved sheet resistance measurements on the backside of IBC solar cells and test structures will be presented. THz and comparative 4-point-probe (4pp) measurements will be presented giving evidence that the terahertz microprobe-based approach can effectively fill the yet present gap of high-resolution contact-free conductivity measurement tools applicable to wafer-scale samples with rough or laserprocessed surfaces.
[1]
H. Kurz,et al.
SiliconPV 2012 generation of defect-related acceptor states by laser doping
,
2012
.
[2]
M. Tinkham.
Energy Gap Interpretation of Experiments on Infrared Transmission through Superconducting Films
,
1956
.
[3]
Ryoichi Fukasawa,et al.
Terahertz imaging of silicon wafers
,
2002
.
[4]
Michael Nagel,et al.
Tapered photoconductive terahertz field probe tip with subwavelength spatial resolution
,
2009
.
[5]
F. J. Castano,et al.
TOWARDS 21% EFFICIENT N-CZ IBC BASED ON SCREEN PRINTING
,
2011
.
[6]
H. Kurz,et al.
Evaluation and investigation of laser doping by a double-Gaussian shaped beam profile
,
2013,
2013 IEEE 39th Photovoltaic Specialists Conference (PVSC).