Browsing by Author "He, J. H."

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GaN-based vertical-cavity surface emitting lasers with sub-milliamp threshold and small divergence angle
(2016-12-12)
Yeh, P. S.
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Chang, C. -C.
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Chen, Y. -T.
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Lin, D. -W.
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Liou, J. -S.
A GaN-based vertical-cavity surface emitting laser (VCSEL) structure featuring a silicon-diffusion-defined current blocking layer for lateral confinement is described. Sub-milliamp threshold currents were achieved for both 3- and 5-mu m-aperture VCSELs under continuous-wave operation at room temperature. The vertical cavity was defined by a top dielectric distributed Bragg reflector (DBR) and a bottom epitaxial DBR. The emission spectrum exhibited a single peak at 411.2 nm with a line-width of 0.4nm and a side mode suppression ratio of more than 10 dB before device packaging. The full-width-at-half-maximum divergence angle of the 3-mu m-aperture VCSEL was as small as approximately 5 degrees which is the lowest number reported. These results implied the 3-mu m-aperture VCSEL was in near single-mode operation. Published by AIP Publishing.
n-ZnO/LaAlO3/p-Si heterojunction for visible-blind UV detection
(2012-03-15)
Tasi, D. S.
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Kang, C. F.
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Wang, H. H.
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Lin, C. A.
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Ke, J. J.
A visible-blind UV photodetector (PD) using a double heterojunction of n-ZnO/LaAlO3 (LAO)/p-Si was demonstrated. Inserted LAO layers exhibit electrical insulating properties and serve as blocking layers for photoexcited electrons from p-Si to n-ZnO, leading to an enhanced rectification ratio and a visible-blind UV detectivity of the n-ZnO/LAO/p-Si PDs due to the high potential barrier between LAO and p-Si layers (similar to 2.0 eV). These results support the use of n-ZnO/LAO/p-Si PDs in the visible-blind UV PDs in a visible-light environment. (C) 2012 Optical Society of America
The Effect of Tensile Strain on Optical Anisotropy and Exciton of m-Plane ZnO
(2015-04-01)
Wang, H. H.
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Tian, J. S.
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Chen, C. Y.
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Huang, H. H.
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Yeh, Y. C.
The near band edge emission of the tensile-strained m-plane ZnO film grown on (112)LaAlO3 substrates shows abnormal low polarization degree (rho = 0.1). The temperature dependency of polarization degree clarifies the origins of different emission peaks. In tensile-strained m-plane ZnO, the [0001] polarized state is upper shifted and is overlapping with the [11 (2) over bar0] polarized state. This phenomenon causes the abnormal low polarization degree and reveals the effect of strain on the emission anisotropy of m-plane ZnO.