Abstract
Experimental and ab initio computational methods are employed to conclusively show that ScN is a semiconductor rather than a semimetal; i.e., there is a gap between the N 2p and the Sc 3d bands. Previous experimental investigators reported, in agreement with band structure calculations showing a band overlap of 0.2 eV, that ScN is a semimetal while others concluded that it is a semiconductor with a band gap larger than 2 eV. We have grown high quality, single crystalline ScN layers on MgO(001) and on TiN(001) buffer layers on MgO(001) by ultrahigh vacuum reactive magnetron sputter deposition. ScN optical properties were determined by transmission, reflection, and spectroscopic ellipsometry while in-situ x-ray and ultraviolet valence band photoelectron spectroscopy were used to determine the density of states (DOS) below the Fermi level. The measured DOS exhibits peaks at 3.8 and 5.2 eV stemming from the N 2p bands and at 15.3 eV due to the N 2s bands. The imaginary part of the measured dielectric function ε2 consists of two primary features due to direct Χ- and Γ-point transitions at photon energies of 2.7 and 3.8 eV, respectively. For comparison, the ScN band structure was calculated using an ab initio Kohn-Sham approach which treats the exchange interactions exactly within density-functional theory. Calculated DOS and the complex dielectric function are in good agreement with our ScN valence-band photoelectron spectra and measured optical properties, respectively. We conclude, combining experimental and computational results, that ScN is a semiconductor with an indirect Γ-Χ bandgap of 1.3±0.3 eV and a direct X-point gap of 2.4±0.3 eV.
| Original language | English |
|---|---|
| Article number | 125119 |
| Pages (from-to) | 1251191-1251199 |
| Number of pages | 9 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 63 |
| Issue number | 12 |
| Publication status | Published - 2001 Jan 1 |
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
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Electronic structure of ScN determined using optical spectroscopy, photoemission, and ab initio calculations. / Gall, D.; Städele, M.; Järrendahl, K.; Petrov, I.; Desjardins, P.; Haasch, R. T.; Lee, Taeyoon; Greene, J. E.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 63, No. 12, 125119, 01.01.2001, p. 1251191-1251199.Research output: Contribution to journal › Article
TY - JOUR
T1 - Electronic structure of ScN determined using optical spectroscopy, photoemission, and ab initio calculations
AU - Gall, D.
AU - Städele, M.
AU - Järrendahl, K.
AU - Petrov, I.
AU - Desjardins, P.
AU - Haasch, R. T.
AU - Lee, Taeyoon
AU - Greene, J. E.
PY - 2001/1/1
Y1 - 2001/1/1
N2 - Experimental and ab initio computational methods are employed to conclusively show that ScN is a semiconductor rather than a semimetal; i.e., there is a gap between the N 2p and the Sc 3d bands. Previous experimental investigators reported, in agreement with band structure calculations showing a band overlap of 0.2 eV, that ScN is a semimetal while others concluded that it is a semiconductor with a band gap larger than 2 eV. We have grown high quality, single crystalline ScN layers on MgO(001) and on TiN(001) buffer layers on MgO(001) by ultrahigh vacuum reactive magnetron sputter deposition. ScN optical properties were determined by transmission, reflection, and spectroscopic ellipsometry while in-situ x-ray and ultraviolet valence band photoelectron spectroscopy were used to determine the density of states (DOS) below the Fermi level. The measured DOS exhibits peaks at 3.8 and 5.2 eV stemming from the N 2p bands and at 15.3 eV due to the N 2s bands. The imaginary part of the measured dielectric function ε2 consists of two primary features due to direct Χ- and Γ-point transitions at photon energies of 2.7 and 3.8 eV, respectively. For comparison, the ScN band structure was calculated using an ab initio Kohn-Sham approach which treats the exchange interactions exactly within density-functional theory. Calculated DOS and the complex dielectric function are in good agreement with our ScN valence-band photoelectron spectra and measured optical properties, respectively. We conclude, combining experimental and computational results, that ScN is a semiconductor with an indirect Γ-Χ bandgap of 1.3±0.3 eV and a direct X-point gap of 2.4±0.3 eV.
AB - Experimental and ab initio computational methods are employed to conclusively show that ScN is a semiconductor rather than a semimetal; i.e., there is a gap between the N 2p and the Sc 3d bands. Previous experimental investigators reported, in agreement with band structure calculations showing a band overlap of 0.2 eV, that ScN is a semimetal while others concluded that it is a semiconductor with a band gap larger than 2 eV. We have grown high quality, single crystalline ScN layers on MgO(001) and on TiN(001) buffer layers on MgO(001) by ultrahigh vacuum reactive magnetron sputter deposition. ScN optical properties were determined by transmission, reflection, and spectroscopic ellipsometry while in-situ x-ray and ultraviolet valence band photoelectron spectroscopy were used to determine the density of states (DOS) below the Fermi level. The measured DOS exhibits peaks at 3.8 and 5.2 eV stemming from the N 2p bands and at 15.3 eV due to the N 2s bands. The imaginary part of the measured dielectric function ε2 consists of two primary features due to direct Χ- and Γ-point transitions at photon energies of 2.7 and 3.8 eV, respectively. For comparison, the ScN band structure was calculated using an ab initio Kohn-Sham approach which treats the exchange interactions exactly within density-functional theory. Calculated DOS and the complex dielectric function are in good agreement with our ScN valence-band photoelectron spectra and measured optical properties, respectively. We conclude, combining experimental and computational results, that ScN is a semiconductor with an indirect Γ-Χ bandgap of 1.3±0.3 eV and a direct X-point gap of 2.4±0.3 eV.
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M3 - Article
AN - SCOPUS:0034894644
VL - 63
SP - 1251191
EP - 1251199
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 12
M1 - 125119
ER -