60th international symposium on molecular spectroscopy discovery: gaas:er system, 1983 the...

60th International Symposium on Molecular Spectroscopy

Discovery: GaAs:Er system, 1983

The coincidence of the transition wavelength with the absorption

minimum of semiconductor-based fibers

The sharp spectrum lines

Disadvantages:

The temperature quenching of the emission intensity

H. Ennen, J. Schneider, G. Pomrenke, A. Axmann, Appl. Phys. Lett. 43, 943 (1983)

Experiment

The temperature insensitive wavelength

Advantages:


Conclusion:

Semiconductor hosts with larger band gaps exhibit less temperature quenching of Er3+ luminescence.

P. N. Favennec, H. L’Haridon, M. Salvi, D. Moutonnet, Y. L. Guillou, Electron. Lett. 25 (1989)

Semiconductor Band Gap

Semiconductor Si GaAs ZnTe CdS GaN

Band Gap (eV) 1.12 1.43 2.26 2.42 3.4

Experiment

Improvement: intensity vs. band gap, 1989


Experiment

M. Thaik, U. Hömmerich, R. N. Schwartz, R. G. Wilson and J. M. Zavada, Appl. Phys. Lett. 71, 2641 (1997)


Theory

The detailed energy splitting of Er3+ center is unknown.

Spin-orbit interaction needs to be considered.

Ligand field effect under different local symmetries should be

studied.

Theoretical calculations are helpful to study transition

mechanism.

Possible transition frequencies under certain local symmetry

could be estimated.

Transition moment needs to be computed explicitly.

Theory

ab initio spin-orbit configuration interaction singles (CIS) and

singles and doubles (CISD) excitation calculations based on

relativistic effective core potentials (RECP) are applied to

calculate energies of the ground and excited states for a series of

Er3+-centered clusters.

Transition dipole moment calculations are performed based on the CI

calculation results.

All of the calculations are carried out by COLUMBUS package.

Calculations Outline


Er substitutes the Ga site

GaN crystals have two crystal structures: zinc blende and wurtzite

Theory

GaN Structure


Theoretical estimate of Ezinc blende-wurzite= 0.952kJ/mol

Td Symmetry Td Symmetry(zinc blende)C3v Symmetry (wurtzite)

Second Shell12 Ga3+ added

ErN49- (Td) ErN4Ga12

27+ (Td) ErN4Ga12N129- (Td)

ErN4Ga12N12Ga69+ (Td)

ErN4Ga1227+ (C3v)

Theory

System GaN: Er Bond Length

(Er—N, Å) 2.17

Bond Length (Ga—N, Å)

1.95


Theory

Brief Review for Er3+

The atomic number of Erbium is 68.

The electron configuration for Er3+ is

1s22s22p63s23p63d104s24p64d104f115s25p6

The ground state term symbol for Er3+ is 4I15/2.

The 1.54 µm PL corresponds to 4I13/24I15/2 transition.

Schematic diagram of the energy levels of a free Er3+ ion and splitting of the 4f subshell levels in the field of Td symmetry.


4I13/2

4I15/2


Theory

RECP and Basis Set Erbium

36-electron core developed by Ermler (unpublished)

1s22s22p63s23p63d104s24p6 Core Corresponding contracted Gaussian cc-pVDZ basis set (Our group)

(5sd3p6f1g)/[3sd2p2f1g]

Nitrogen

2-electron core developed by Christiansen (1985)

1s2 Core Corresponding contracted Gaussian cc-pVDZ basis set (Pitzer)

(4s4p1d)/[3s2p1d] Gallium

28-electron core developed by Ermler (1986)

1s22s22p63s23p63d10 Core


Er cc-pVDZ Basis Set (5sd3p6f1g)/[3sd2p2f1g]

Exponents Contraction Contraction Contraction sd 165.9000000

7.4040000 2.6340000 1.0520000 0.2831000

-0.0001048 -0.0316947 0.0845995 0.8471365 0.1818435

-0.0026226 0.5788017 0.5046548 0.0339234 0.0117298

0.0007090 -0.1766013 -0.1244033 0.3246558 0.8251623

p 2.6430000 0.8467000 0.3113000

-0.1715083 0.6549941 0.5054589

0.0000000 -0.2862934 1.0000000

f 101.8000000 32.6200000

12.5400000 4.9670000 1.8530000 0.5859000

0.0188562 0.1083544 0.2899235 0.4191380 0.3798237 0.2124501

0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 1.0000000

g 3.3730000 1.0000000

Theory

For virtual p orbital:

Augmented primitive is used.

145

1' mmmmm For virtual f orbital:

Freeing diffuse primitive method is applied.

For g polarization orbital:

CISD method is employed to optimize the exponent.

P. A. Christiansen, J. Chem. Phys. 112 , 10070 (2000)


Theory


Theory

Reference Space

CIS

4f orbitals of Er3+ (small reference, 57,239 CSFs)

5s, 5p, 4f orbitals of Er3+ and 2s, 2p orbitals of N3-

(large reference, 888,979 CSFs)

CISD

4f orbitals of Er3+ (small reference, 6,504,680 CSFs)

5s, 5p, 4f orbitals of Er3+ and 2s, 2p orbitals of N3-

(large reference, over one billion CSFs)


29 atoms

35 atoms

4I13/2 E1/2 6137.55 6159.12

G3/2 6117.12 6135.64

E5/2 6090.93 6104.59

E5/2 6009.36 6016.82

G3/2 5990.28 5994.71

4I15/2 G3/2 215.00 238.31

G3/2 196.71 212.71

E5/2 33.49 49.11

G3/2 18.63 22.13

E1/2 0.00 0.00

Theory

State Energy (cm-1)

Electric Transitions

E1/2—E5/2

Electric dipole moment operator belongs to F2 irreducible representation under Td symmetry.

E1/2—G3/2 E5/2—G3/2 G3/2—G3/2

22 possible transitions wavelengths correspond to 4I13/24I15/2.

Theory


Need to know the initial populations of the upper sublevels to compare to the spectrum.

ErN4Ga12N12Ga6

9+ Cluster

1.62 1.64 1.66 1.68 1.7 1.72 1.740

1 106

2 106

3 106

4 106

5 106

Transition Wavelength (um)

Tra

nsit

ion

Mom

ent^

2 (e

*boh

r)^2

y

x

Theory


2nd G3/2->2nd G3/2G3/2: from 4I13/2

G3/2: from 4I15/2

Transition Moments Squares

Conclusions and Future Work


Td clusters show a converged splitting pattern with the E1/2 state as the ground state.

1.54 µm PL is tentatively assigned to the transition between 2nd G3/2 of 4I13/2 and 2nd G3/2 of 4I15/2.

Large clusters for both zinc blende and wurzite should be studied.

60th international symposium on molecular spectroscopy discovery: gaas:er system, 1983 the...

Documents

electron core

series of er3

er3 center

transition moment

theoretical calculations

transition wavelength

4i1324i152 transition

electron configuration