CuInSe2

Basic Info

Melting temperature 1: 1260K

Crystal Structure 1: Chalcopyrite lattice

Space Group: I42d

Z = 4

a = 5.781 Å

c = 11.552 Å

c/a = 2

A graph showing peak intensities (intensity vs. 2-theta) can be found at reference 2

The unit cell can be seen in reference 3.

PV Applications:

Conversion efficiencies of 17.8% have been reached for vapor-deposited CIS cells

The chalcopyrite structure of ternary I-III-VI2 compounds have high absorption coefficients making CIS well-suited for solar cells

CuInSe2 is the absorber layer

Basic Parameters at 300 K:

Density 1: 5.77g/cm3

Dielectric Constants 1: ɛ(0) = 15.2  E ‖ c

 ɛ(0) = 16.0  E⊥c

ɛ(∞) = 8.5  E ‖ c

ɛ(∞) = 9.5  E⊥c

Band Structure and carrier concentration 1:

Single Crystals:

p-type

μn  (6±3) cm2/V-s

μp  (3.1±0.15) cm2/V-s

p   5x1015 cm-3

Bandgap of 1.02 eV

A graph of the band structure of CuInSe2 can be seen at reference 1.

Temperature Dependences:

Energy Gap Narrowing at High Doping Levels 1:

Energy Gap

Eg.dir  (1.010 ± 0.001) eV single crystal

dEg/dT   -1.1x10-4 eV/K T= 100…300K

Effective Masses and Density of States

Effective Masses 1:

The Fermi surface of electrons is spherical and located at the center of the Brillouin zone.

Cyclotron mass value m*c  0.0822 m0

Eff. Mass at minimum of conduction band m*0  0.0772 m0

mn = mp  0.087 m0

Donors and Acceptors 4:

The acceptor levels are at 0.020 eV and 0.028 eV above the valence band and the donor levels are at 0.012 eV and 0.18 eV below the conduction band.

Electrical Properties

Exciton binding energy 1: 4.3meV  T = 2K

Splitting energies (at Γ)

Δso   0.8 eV

Δcf   +0.006 eV  T = 77 K

Δso   0.23 eV  T = 77 K

Basic Parameters of Electrical Properties:

Mobility and Hall Effect 1:

A graph showing Electron mobility vs. temperature for four n-type samples can be found at reference 1.

A graph of the Resistivity and Hall coefficient vs. reciprocal temperature for four p-type samples can be found at reference 1.

Optical properties 1:

Refractive index: n = 2.5-2.7    hv = 0.5-0.9 eV

Absorption coefficient 5: 104 cm-1

Thermal properties:

Coefficient of thermal expansion 1:

X-ray studies on powder prepared from single crystals

Parallel: 7.90x10-6 1/K along c – axis

Perpendicular: 11.23x10-6 along a – axis

Debye temperature 1: 243.7 K

A graph of electron mobility vs. temperature can be found at reference 1.

Mechanical properties:

Bulk modulus 1: 4.82x1012 Pa

Elastic Constants

Second order elastic moduli 1: T=300 K

C11  9.70x1010 N/m

C33  10.89x1010 N/m

C44  3.62x1010 N/m

C66  3.16x1010 N/m

C12  5.97x1010 N/m

C13  8.60x1010 N/m

Acoustic Wave Speeds:

Sound velocity [1]:

υL  3.77x105  cm/s

υT   2.10x105  cm/s

Phonon Frequencies

A graph of the phonon dispersion curves of TA[100], LA[100], TA1[110], TA2[110], LA[1110], TO2[110], LA[001], TA[001] and TO[001] modes can be seen at reference 1.

Developed at the University of Utah primarily by undergraduate students Jeff Provost and Carina Hahn working with Prof. Mike Scarpulla. Caitlin Arndt, Christian Robert, Katie Furse, Jash Sayani, and Liz Lund also contributed. The work was fully supported by the US National Science Foundation under the Materials World Network program award 1008302. These pages are a work in progress and we solicit input from knowledgeable parties around the world for more accurate or additional information. Contact [email protected] with such suggestions.