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Proceedings Paper

Heterojunctions based on transparent oxidic layer and silicon for electronic and optoelectronic device applications
Author(s): Florin Constantin Comanescu; Munizer Purica; Felicia Iacomi; Elena Budianu; Paul Schiopu
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Paper Abstract

The aim of the present work is to prepare, test and analyze the electrical and optical characteristics of the p- NiO/n-Si and n-ZnO/p-Si heterojunctions as building blocks in semiconductor devices. p-NiO thin films of 75 nm have been prepared by thermal oxidation of Ni metallic films of 50 nm deposited by e-beam high vacuum evaporation technique on n type silicon wafer with 30 Ω cm resistivity. The oxidation processes of nickel samples are performed at 430oC for 60 min in a controlled ambient of oxygen and argon maintaining the oxygen concentration of 70%. The structural characteristics observed by X - ray diffraction method showed a polycrystalline structure with strong peaks corresponding to cubic NiO. p-NiO / (n/n+) Si heterojunctions I-V characteristics revealed that p-type NiO thin films have been obtained and a value of ~2.2 V for forward threshold voltage. n-ZnO thin layers of about 200 nm thickness, doped with aluminum on 30 Ωcm resistivity p type silicon epitaxial wafers were obtained by spin coating, layer by layer, using zinc acetate (Zn(CH3COO)2⋅2H2O) and aluminum nitrate (Al(NO3)3⋅9H2O) with Al/ Al+Zn ratio in range 0.5 - 1.5 % followed by thermal treatment at 475 °C for 15 minutes. The obtained thin layers have a high transparency T>85% for NiO and >70 % for ZnO:Al) over a large spectral range and a low resistivity, ρ~10-4 Ωcm. The I-V characteristics of p-NiO/n– Si shows that this heterojunction has rectifying properties with turn on voltage in the range 1.5- 2V and reverse breakdown voltage >10 V. By fitting the forward voltage we have obtained for p-NiO/n-Si a series resistance id RS=16 kΩ, an ideality factor of >10 and a barrier height of 0.648 eV. The optical response of n-ZnO/p- Si heterojunction was investigated at λp = 475 nm and the measured values of the photocurrent about 10 μA confirms the possibility to use them as ultraviolet radiation detectors.

Paper Details

Date Published: 1 November 2012
PDF: 6 pages
Proc. SPIE 8411, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VI, 84112C (1 November 2012); doi: 10.1117/12.966463
Show Author Affiliations
Florin Constantin Comanescu, IMT Bucharest (Romania)
Univ. Politehnica of Bucharest (Romania)
Munizer Purica, IMT Bucharest (Romania)
Felicia Iacomi, Univ. Alexandru Ioan Cuza (Romania)
Elena Budianu, IMT Bucharest (Romania)
Paul Schiopu, Politehnica Univ. of Bucharest (Romania)

Published in SPIE Proceedings Vol. 8411:
Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VI
Paul Schiopu; Razvan Tamas, Editor(s)

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