Cu and Cd sulphides for photovoltaic applications Tommaso Baroni*, - - PowerPoint PPT Presentation

Surface X-Ray Diffraction study of a bi-layer junction based on Cu and Cd sulphides for photovoltaic applications

Tommaso Baroni*, Francesco Di Benedetto, Andrea Giaccherini, Enrico Berretti, Francesca Russo, Annalisa Guerri, Massimo Innocenti, Francesco Carlà, Roberto Felici

https://www.bloomberg.com/graphics/2015-whats-warming-the-world/

‘What’s really warming the world’

https://www.nrel.gov/pv/cell-efficiency.html

EH1 - ID03 beamline

S

Cd X 60

Ag(111)

Cu X 60

S

(Cu2S)60/(CdS)60/Ag(111)

120 E-ALD cycles (~25nm)

Sample preparation

(CdS)60/Ag(111) structure vs N° Cu2S cycle

L 0.0E+00 5.0E-04 1.0E-03 1.5E-03 2.0E-03 2.5E-03 2.23 2.236 2.242 2.248 2.254 2.26 2.266 2.272 2.278 2.284 2.29 2.296 2.302 2.308 2.314 2.32 2.326 2.332 2.338 2.344 2.35 2.356 2.362 2.368 2.374 2.38 2.386 2.392 2.398 2.404 2.41 2.416 2.422 2.428 2.434 2.44

Intensità (a.u.) l (r.l.u.)

(012)CdS l-scan

6 12 18 24 30 36 42 48 54 60

0.0E+00 5.0E-04 1.0E-03 1.5E-03 2.0E-03 2.5E-03 3.0E-03 0.628 0.631 0.634 0.637 0.64 0.643 0.646 0.649 0.652 0.655 0.658 0.661 0.664 0.667 0.67 0.673 0.676 0.679 0.682 0.685 0.688 0.691 0.694 0.697 0.7 0.703 0.706 0.709

Intensità (a.u.) k (r.l.u.)

(012)CdS k-scan

6 12 18 24 30 36 42 48 54 60

2.32 2.325 2.33 2.335 2.34 6 12 18 24 30 36 42 48 54 60 0.65 0.655 0.66 0.665 0.67 0.675 0.68 6 12 18 24 30 36 42 48 54 60

ҧ 𝒎 = 𝟑. 𝟒𝟒𝟏 ± 𝟏. 𝟏𝟏𝟒 𝐬. 𝐦. 𝐯. ഥ 𝒍 = 𝟏. 𝟕𝟕𝟖 ± 𝟏. 𝟏𝟏𝟒 𝐬. 𝐦. 𝐯.

L

Greenockite 𝑸𝟕𝟒𝒏𝒅

𝑏 = 𝑐 = 𝟓. 𝟐𝟒𝟖 Å; 𝑑 = 𝟕. 𝟖𝟐𝟓 Å 𝛽 = 𝛾 = 90°; 𝛿 = 120° V = 𝟘𝟘. 𝟔𝟑 Å𝟒

(CdS)60/Ag(111) ?

𝑏 = 𝑐 = 𝟓. 𝟒𝟒𝟑 Å; 𝑑 = 𝟕. 𝟏𝟖𝟔 Å 𝛽 = 𝛾 = 90°; 𝛿 = 120° V = 𝟘𝟗. 𝟖𝟒 ± 𝟏. 𝟒𝟖 Å𝟒

(CdS)60/Ag(111) 2-D BINoculars map

L

h’ (rlu) k (rlu) k (rlu) h’ (rlu)

(Cu2S)60/(CdS)60/Ag(111)

(MA3071)

(Cu2S)60/Ag(111)

(ma2082)

𝑑𝑑ℎ𝑏𝑚𝑑𝑝𝑑𝑗𝑢𝑓 = 13.494 Å 𝑏 = 𝑐 = 27.41 ± 0.04 Å; 𝑑 = 6.76 ± 0.03 Å 𝛽 = 𝛾 = 90°; 𝛿 = 120°

(Cu (Cu2S) S)60

60/(

/(CdS)60

60/Ag(111)

MA3071

(0 0.73 0.2-6)Cu

Cu2S S l-scan and Cu2S cell parameters

Conclusions

L

• MA3071 is the first in-situ SXRD experiment which features an E-ALD bi-layer junction of Cu2S/CdS/Ag(111).
• The SXRD in-situ analysis highlights the profound epitaxial relationship existing between the films and the bulk,

consequent to the homogenisation of the metrics of the CdS and the Cu2S structures to values commensurate to the surface periodicity of the substrate.

• The (CdS)60/Ag(111) develops an elementary cell with crystallographic axes parallel to those of the surface cell of the

Ag(111); the comparison with the structure of greenockite suggests a compensation mechanism related to the strain imposed by the film growth on the crystallographic Ag(111) surface.

• The positions in the reciprocal space of the Cu2S reflections is compatible with an pseudo-hexagonal pattern rotated

by 30 ° with respect to the surface cell cell of the substrate; the data suggest a hexagonal chalcocite-like structure with a planarization of the S layers, as a result of the strong epitaxial relationship existing with the CdS below and as already noticed in relation to a Cu2S/Ag(111) E-ALD deposit by Giaccherini et al. (1).

• This study confirms E-ALD as an energy efficient method for the growth of semiconducting heterostructures with

tailored properties using low cost/environmental-impact materials.

1) Giaccherini et al. (2017), Scientific Reports | 7: 1615 | DOI:10.1038/s41598-017-01717-0