Nanoscale mapping of carrier collection in single nanowire solar cells using X-ray beam induced current

Abstract

Nanofocused X-ray beam induced current (XBIC) is used to quantitatively map the spatially dependent carrier collection probability within single nanowires.

Combining Nanofocused X-Rays with Electrical Measurements at the NanoMAX Beamline

“…The XBIC map in Figure 4c sheds light on the underlying carrier collection mechanism of the nanowire device [11,48]. The signal is generated in the middle segment, approximately corresponding to the depletion region of the solar cell.…”

“…The tested nanodevice was a horizontal contacted single nanowire device with a p-i-n doped InP nanowire (Figure 2c,d). A similar type of nanowires has been developed for the next generation solar cells [23], which have already been thoroughly studied using nano-XBIC and XRF in our previous works [10,11]. These nanowire devices were fabricated on a 0.25 × 0.25 mm Si 3 N 4 membrane window on a 3 × 5 mm Si chip from Silson (Southam, Warwickshire, England).…”

“…X-rays have a long penetration depth compared with electron and optical beams [1], and modern X-ray optics can provide nanofocusing at the range of tens of nanometers [2,3]. This development has made it possible to investigate complete single semiconductor nanostructures [4][5][6][7][8][9][10][11]. By combining the nanofocused X-ray probe with an applied electrical bias as well as electrical current detection, nanodevices can be investigated in more or less realistic operational conditions.…”

“…Unlike scanning XRD, which has been frequently used to study nanowires [15,17,19,[29][30][31][32][33][34][35], there have only been a few examples of nanowire devices studied using XBIC [8,9,11,36]. XBIC has been employed for studying solar cells since the early 2000s [37,38], when it was mostly used to examine grain boundaries and precipitated metal in polycrystalline silicon for solar cells at micrometer resolution [39][40][41].…”

X-ray Beam Induced Current Measurements for Multi-Modal X-ray Microscopy of Solar Cells

“…With a wealth of different measurement techniques at a scanning X-ray microscope, it becomes possible to simultaneously study not just one, but many different aspects of solar cells within multi-modal measurements and to correlate the observed characteristics. For example, X-ray beam induced current (XBIC) measurements have successfully been combined with X-ray fluorescence (XRF) 7,18,19 , Xray excited optical luminescence (XEOL) 20,21 , and X-ray diffraction (XRD) 22 to correlate the electrical performance with composition, optical performance, and structure, respectively 23 .…”