Browsing by Author "Liu, W. R."

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Carrier dynamics of thin ZnO epifilm above band-gap states
(2009)
Ou, Po-Chi
;
Lin, Ja-Hon
;
Chang, C. A.
;
Liu, W. R.
;
Hsieh, Wen-Feng
Ultrafast carrier dynamics of ZnO epifilm were investigated by the pump probe meausrement Relative fast occruring and recovery of band gap renormalizaion following the band filling effect will result in transmission change at 362 nm.
Surface-bound-exciton emission associated with domain interfaces in m-plane ZnO films
(1970-01-01)
Kuo, C. C.
;
Lin, B. H.
;
Yang, Song
;
Liu, W. R.
;
Hsieh, W. F.
"Small amount of (10 (1) over bar3)(ZnO) domains were found in the m-plane ZnO films grown on m-sapphire by pulsed laser deposition, which provide strain relaxation of the m-ZnO matrix behaving as a low strain layer. Through carefully correlating low-temperature polarized photoluminescence spectra with the x-ray diffraction peak intensity ratio of (10 (1) over bar3)(ZnO)/(10 (1) over bar0)(ZnO) of the samples grown at different temperature and after thermal treatment, we found that the broad-band emission around 3.17 eV may result from the interface defects trapped excitons at the boundaries between the (10 (1) over bar3)(ZnO) domains and the m-ZnO matrix. The more (10 (1) over bar3)(ZnO) domains in the m-ZnO layer cause the more surface boundary that makes the stronger surface-bound-exciton emission. And the a-axes of both the (10 (1) over bar3)(ZnO) domains and the m-ZnO matrix are aligned with the c-axis of the sapphire (alpha-Al2O3) substrate. The c-axis of the (10 (1) over bar3)(ZnO) domains rotates by about +/- 59 degrees against the common a-axis of the m-ZnO. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4732140]"
The Growth of an Epitaxial ZnO Film on Si(111) with a Gd(2)O(3)(Ga(2)O(3)) Buffer Layer
(2011-07-01)
Lin, B. H.
;
Liu, W. R.
;
Yang, S.
;
Kuo, C. C.
;
Hsu, C. -H.
High-quality (0001)-oriented ZnO epitaxial films have been grown by pulsed laser deposition on Si(111) buffered with a nanometer-thick Gd(2)O(3)(Ga(2)O(3)), GGO, layer. The structural characteristics of the ZnO epi-layers were studied by X-ray diffraction and transmission electron microscopy (TEM). The in-plane epitaxial relationship between the wurtzite ZnO, cubic GGO, and cubic Si follows {10 (1) over bar0}(ZNO)parallel to{4 (22) over bar}(Gd2O3)parallel to{(4) over bar 22}(Si) and the ZnO/GGO interface can be described by the domain matching epitaxy. TEM contrast analysis reveals that the major defect structures in the ZnO films are edge-type threading dislocations and intrinsic basal plane stacking faults. All the ZnO epi-films studied are under a tensile biaxial strain, but no cracks were found. Temperature-dependent photoluminescence results show the excellent optical properties of the obtained ZnO layers, and the origins of the spectral features are discussed.
The Growth of an Epitaxial ZnO Film on Si(111) with a Gd2O3(Ga2O3) Buffer Layer
(2011-07-01)
Lin, B. H.
;
Liu, W. R.
;
Yang, S.
;
Kuo, C. C.
;
Hsu, C. -H.
High-quality (0001)-oriented ZnO epitaxial films have been grown by pulsed laser deposition on Si(111) buffered with a nanometer-thick Gd2O3(Ga2O3), GGO, layer. The structural characteristics of the ZnO epi-layers were studied by X-ray diffraction and transmission electron microscopy (TEM). The in-plane epitaxial relationship between the wurtzite ZnO, cubic GGO, and cubic Si follows {10 (1) over bar0}(ZNO)parallel to{4 (22) over bar}(Gd2O3)parallel to{(4) over bar 22}(Si) and the ZnO/GGO interface can be described by the domain matching epitaxy. TEM contrast analysis reveals that the major defect structures in the ZnO films are edge-type threading dislocations and intrinsic basal plane stacking faults. All the ZnO epi-films studied are under a tensile biaxial strain, but no cracks were found. Temperature-dependent photoluminescence results show the excellent optical properties of the obtained ZnO layers, and the origins of the spectral features are discussed.