Enhancement Of Free Exciton Peak Intensity In Reactively Sputtered ZnO Thin Films On (0001) Al2O3

2007 ◽  
Author(s):  
S. Tüzemen ◽  
Emre Gür ◽  
T. Yildirim ◽  
G. Xiong ◽  
R. T. Williams
Keyword(s):  
Thin Films ◽  
Free Exciton ◽  
Zno Thin Films ◽  
Exciton Peak ◽  
Peak Intensity

scholarly journals Study of Ultraviolet Emission Spectra in ZnO Thin Films

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Y. M. Lu ◽  
X. P. Li ◽  
P. J. Cao ◽  
S. C. Su ◽  
F. Jia ◽  
...  
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Free Exciton ◽  
Emission Spectra ◽  
Low Energy ◽  
Zno Thin Films ◽  
Ultraviolet Emission ◽  
Exciton Transition ◽  
Pl Spectra ◽  
Uv Emission

Photoluminescence (PL) of ZnO thin films prepared on c-Al2O3substrates by pulsed laser deposition (PLD) are investigated. For all samples, roomtemperature (RT) spectra show a strong band-edge ultraviolet (UV) emission with a pronounced low-energy band tail. The origin of this UV emission is analyzed by the temperature dependence of PL spectra. The result shows that the UV emission at RT contains different recombination processes. At low temperature donor-bound exciton (D0X) emission plays a major role in PL spectra, while the free exciton transition (FX) gradually dominates the spectrum with increasing temperatures. It notes that at low temperature an emission band (FA) appears in low energy side of D0X and FX and can survive up to RT. Further confirmation shows that the origin of the band FA can be attributed to the transitions of conduction band electrons to acceptors (e, A0), in which the acceptor binding energy is estimated to be approximately 121 meV. It is concluded that at room temperature UV emission originates from the corporate contributions of the free exciton and free electrons-to-acceptor transitions.

Optical properties and electrical characterization of p-type ZnO thin films prepared by thermally oxiding Zn3N2 thin films

2003 ◽  
Vol 18 (1) ◽  
pp. 8-13 ◽  
Author(s):  
B. S. Li ◽  
Y. C. Liu ◽  
Z. Z. Zhi ◽  
D. Z. Shen ◽  
Y. M. Lu ◽  
...  
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Deep Level ◽  
Free Exciton ◽  
Hexagonal Structure ◽  
Fused Silica ◽  
Zno Thin Films ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Simple Method

In this paper, we report a simple method for preparing p-type ZnO thin films by thermal oxidization of Zn3N2 thin films. The Zn3N2 films were grown on fused silica substrates by using plasma-enhanced chemical vapor deposition from a Zn(C2H5)2 and NH3 gas mixture. The Zn3N2 film with a cubic antibixbyite structure transformed to ZnO:N with a hexagonal structure as the annealing temperature reached 500 °C. When the annealing temperature reached 700 °C, a high-quality p-type ZnO film with a carrier density of 4.16 × 1017 cm−3 was obtained, for which the film showed a strong near-band-edge emission at 3.30 eV without deep-level emission, and the full width at half-maximum of the photoluminescence spectrum was 120 meV at room temperature. The origin of the ultraviolet band was the overlap of free exciton and the bound exciton. The N concentration was as high as 1021 cm−3, which could be controlled by adjusting the parameters of the annealing processes.

Activation of N-Acceptor in MOCVD-ZnSe by Excimer Laser Annealing

1992 ◽  
Vol 281 ◽  
Author(s):  
Nallan Padmapani ◽  
G. F. Neumark ◽  
N. Taskar ◽  
D. Dorman
Keyword(s):  
Excimer Laser ◽  
Laser Annealing ◽  
Free Exciton ◽  
Plasma Source ◽  
Exciton Peak ◽  
Electrical Measurements ◽  
Excimer Laser Annealing ◽  
Recent Success ◽  
Peak Intensity ◽  
P Type

ABSTRACTThe recent success in obtaining blue-green diode lasers using ZnSe-based heterostructures has been mainly due to the successful p-doping of ZnSe using a N plasma source in an MBE system. P-type ZnSe can also be grown by MOCVD, using NH3 as the dopant source. Dopant concentrations of up to 1018 cm−3 have been obtained but net acceptor concentrations are in the range of only about 1015 cm−3 Activation of the remaining N has been achieved to some extent (NA -ND∼3*1016cm−3 ) by rapid thermal annealing. However, this has had limited success. We have used fast surface annealing by an excimer laser to activate the N. We have observed an increase in the ratio of Acceptor Bound Exciton peak intensity to Free Exciton peak intensity on annealing and this effect increases as we increase the laser power density from 10 to 30 MW/cm2. Electrical measurements ( C-V ) give a net acceptor concentration of ∼2*1016 cm−3 and thus confirm the increase in carrier concentration after annealing.

Defects in Irradiated ZnO Thin Films Studied by Photoluminescence and Photoconductivity

2010 ◽  
Vol 1268 ◽  
Author(s):  
Reinhard Schwarz ◽  
Rachid Ayouchi ◽  
Marta Brandão ◽  
Carlos Marques ◽  
Eduardo Alves ◽  
...  
Keyword(s):  
Thin Films ◽  
Radiative Recombination ◽  
Ion Beam ◽  
Pulsed Laser ◽  
Zno Thin Films ◽  
Exciton Peak ◽  
Pl Spectra ◽  
Helium Ion ◽  
Deposited Films ◽  
Hecd Laser

AbstractPulsed-laser-deposited ZnO thin films were exposed to a 1.5 MeV helium ion beam to study the changes in radiative and non-radiative recombination. We first measured photoluminescence (PL) spectra at 4.2 K excited with the 325 nm line of a HeCd laser. The as-deposited films showed a donor-bound exciton peak at 3.3567 eV attributed to Zn interstitials. After irradiation the donor-bound-exciton dominated PL spectra shifted to acceptor-bound behaviour with a signal at 3.3519 eV, tentatively attributed to Li or Na acceptors. In contrast to the approximately 30 % decrease of the PL signal near the band edge, we observed a strong concomitant enhancement of the green/orange PL band, located between 2.1 eV and 2.8 eV, by a factor of over 4. Candidates for those transitions are Li impurities and/or O vacancies. For comparison, the steady-state photocurrent decreased strongly in the irradiated region, which can also be attributed to increased non-radiative recombination through oxygen-related defects.

Influence of N Dopant on the Electric and Magnetic Properties of Co Doped ZnO Thin Films

2010 ◽  
Vol 25 (7) ◽  
pp. 711-716 ◽  
Author(s):  
Xue-Tao WANG ◽  
Li-Ping ZHU ◽  
Zhi-Gao YE ◽  
Zhi-Zhen YE ◽  
Bing-Hui ZHAO
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Zno Thin Films ◽  
Doped Zno ◽  
Co Doped
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