Change search
ReferencesLink to record
Permanent link

Direct link
Temperature dependence of the photoelectric conversion quantum efficiency of 4H-SiC Schottky UV photodetectors
Show others and affiliations
2005 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 20, no 8, 710-715 p.Article in journal (Refereed) Published
Abstract [en]

Ultraviolet Schottky photodetectors based on n-4H-SiC (N-d - N-a = 4 x 10(15) cm(-3)) epitaxial layers of high purity have been fabricated. Their spectral sensitivity range is 3.2-5.3 eV peaking at 4.9 eV (quantum efficiency is about similar to 0.3 electron/photon), which is close to the bactericidal ultraviolet radiation spectrum. The temperature dependence of the quantum efficiency of 4H-SiC Schottky structure has been investigated to determine the temperature stability and the mechanism of the photoelectric conversion process. At low temperatures (78-175 K) the quantum efficiency increases with increasing temperature for all photon energy values and then tends to saturate. We suppose that some imperfections in the space-charge region act as traps that capture both photoelectrons and photoholes. After some time the trapped electron-hole pairs recombine due to the tunnelling effect. At high temperatures (more than 300 K), the second enhancement region of the quantum efficiency is observed in the photon energy range of 3.2-4.5 eV. It is connected with a phonon contribution to indirect optical transitions between the valence band and the M-point of the conduction band. When the photon energy is close to a direct optical transition threshold this enhancement region disappears. This threshold is estimated to be 4.9 eV. At photon energies more than 5 eV a drastic fall of the quantum efficiency has been observed throughout the temperature interval. We propose that in this case the photoelectrons and photoholes are bound to form hot excitons in the space-charge region due to the Brillouin zone singularity, and do not contribute to the following photoelectroconversion process.

Place, publisher, year, edition, pages
2005. Vol. 20, no 8, 710-715 p.
Keyword [en]
URN: urn:nbn:se:kth:diva-15017DOI: 10.1088/0268-1242/20/8/010ISI: 000231674100014ScopusID: 2-s2.0-22844442549OAI: diva2:333058
QC 20100525Available from: 2010-08-05 Created: 2010-08-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Hallén, Anders.
By organisation
Microelectronics and Information Technology, IMIT
In the same journal
Semiconductor Science and Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 28 hits
ReferencesLink to record
Permanent link

Direct link