Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 92: Poster Session: II-VI Semiconductors & ZnO and related Materials

HL 92.18: Poster

Donnerstag, 29. März 2012, 16:00–19:00, Poster D

Wavelength selective photodetectors based on (Mg,Zn)O-heterostructures — •Zhipeng Zhang, Holger von Wenckstern, Matthias Schmidt, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstraße 5, 04103, Leipzig

We report on ultraviolet metal-semiconductor-metal (MSM) photodetectors based on Mg_yZn_1−yO/Mg_xZn_1−xO heterostructures (0<y<x≤0.5, wurtzite modification) allowing to design wavelength selective detectors with narrow bandwidth [1]. The Mg_xZn_1−xO thin film acts as optical edge filter and the Mg_yZn_1−yO layer is the active layer of the devices. Therefore, ideally only light in a defined photon energy range of E_g^y<E_ph<E_g^x contributes to the photoresponse. The spectral bandwidth is given by the bandgap difference Δ E_g of the two (Mg,Zn)O layers. The interdigital MSM-electrodes were fabricated by photolithography and reactive dc-sputtering of palladium (Pd) with an additional metallic Pd-capping layer [2]. A FWHM of only 7 nm was achieved for a photodetector operating around 3.4 eV and the center of band was shifted by using different y:x-combinations between 370 and 325 nm. A maximum spectral photoresponse of about 1.8 A/W was achieved. An internal gain mechanism in the device was observed and is attributed to trapping of minority carriers at PdO_z/(Mg,Zn)O-interface [3].

[1]: Z. Zhang et al., Appl. Phys. Lett. 99, 083502 (2011)

[2]: A. Lajn et al., J. Vac. Sci. Technol. B, 27, 1769 (2009)

[3]: O. Katz et al., Appl. Phys. Lett. 84, 4092 (2004)