Anisotropic phonon properties and effective electron mass in α-Ga2O3
The ordinary and extraordinary infrared dielectric functions of α-Ga2O3 thin films with the corundum structure were investigated. The films were grown by mist chemical vapor epitaxy on ( 10 1 ¯ 0 ) sapphire substrates in ( 10 1 ¯ 0 ) surface orientation. They were doped by the donor tin with the res...
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| Published in: | Applied physics letters 2019-04, Vol.114 (14) |
|---|---|
| Main Authors: | , , , , , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The ordinary and extraordinary infrared dielectric functions of α-Ga2O3 thin films with the corundum structure were investigated. The films were grown by mist chemical vapor epitaxy on
(
10
1
¯
0
) sapphire substrates in
(
10
1
¯
0
) surface orientation. They were doped by the donor tin with the resulting free-electron concentrations between 1017 and 1019 cm−3. Structural characterization revealed the absence of strain and the high crystallographic quality of the samples. It allows one to resolve all 7 Raman modes. 5 out of 6 infrared active transverse optical phonon modes lie in the investigated wave number range >250 cm−1, and are unambiguously identified by spectroscopic ellipsometry. For the highest doped sample, the free-carrier contribution (plasmon) to the infrared spectra allowed accurate determination of effective electron masses. They are
m
⊥
*
=
(
0.297
±
0.010
)
m
0 (perpendicular to [0001]) and
m
|
|
*
=
(
0.316
±
0.007
)
m
0 (parallel to [0001]) for an electron concentration of n = 1.1 × 1019 cm−3. |
|---|---|
| ISSN: | 0003-6951 1077-3118 |