Browsing by Author "Su, YK"

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1.3-mu m InAs-InGaAs quantum-dot vertical-cavity surface-emitting laser with fully doped DBRs grown by MBE
(2006-01-01)
Yu, HC
;
Wang, JS
;
Su, YK
;
Chang, SJ
;
Lai, FI
We report InAs-InGaAs quantum-dot vertical-cavity surface-emitting lasers (VCSELs) grown by molecular beam epitaxy with fully doped n- and p-doped AlGaAs distributed Bragg reflectors and including an AlAs layer to form a current and waveguiding aperture. The metal contacts are deposited on a topmost p(+) (GaAs)-Ga-. contact layer and on the bottom surface of the n(+)-GaAs substrate. This conventional selectively oxidized top-emitting device configuration avoids the added complexity of fabricating intracavity or coplanar ohmic contacts. The VCSELs operate continuous-wave at room temperature with peak output powers of 0.33 mW and differential slope efficiencies up to 0.23 W/A. The peak lasing wavelengths are near 1.275 mu m, with a sidemode suppression ratio of 28 dB.
Evolution of conduction and interface states of laterally wet-oxidized AlGaAs with oxidation time
(2006-01-15)
Chen, JF
;
Hsiao, RS
;
Hung, WK
;
Wang, JS
;
Chi, JY
The conduction and interface states of laterally wet-oxidized GaAs-AlGaAs-GaAs structures after various oxidation times are investigated. Effective current blocking is achieved after 150 min oxidation and the conduction of current through the oxidized AlGaAs layer is controlled by the Poole-Frenkel mechanism, from which a relative dielectric constant of 7.07 is obtained. At an oxidation time of 15 min, capacitance-voltage spectra exhibit capacitance dispersion over frequency, implying the presence of an interface state. The intensity of the dispersion increases with increasing the oxidation time and admittance spectroscopy reveals a significant interface state at similar to 0.28 eV at 45 min. Further increasing the oxidation time to 150 min broadens the interface state to a set of continuous interface states from 0.19-0.31 eV with decreasing densities from 3x10(11) to 0.9x10(11) eV(-1) cm(-2) and generates fixed charges of about 9.1x10(11) cm(-2) in the oxidized layer. By comparison to a similar trap in a relaxed InGaAs/GaAs, the interface state is tentatively assigned to the interaction of residual As with dislocations. (c) 2006 American Institute of Physics.
Improvement of high-speed oxide-confined vertical-cavity surface-emitting lasers
(2004-04-01)
Yu, HC
;
Chang, SJ
;
Su, YK
;
Sung, CP
;
Yang, HP
High-speed vertical-cavity surface-emitting lasers that could be modulated up to 10 Giga-bit-per-second (Gbps) were accomplished by using additional proton implantation to reduce the parasitic capacitance. The eye diagram of the implanted device shows a noticeable improvement when compared with those devices without implantation. In contrast to previous reports, moreover, the output power-current-voltage (L-I-V) characteristics of the fabricated devices ill this study show excellent consistency between before and after implantation. The high-temperature lifetime of devices fabricated with a similar process has already exceeded 8100 h up to the present day.
Liquid phase deposited SiO2 on GaN
(2003-04-29)
Wu, HR
;
Lee, KW
;
Nian, TB
;
Chou, DW
;
Wu, JJH
An efficient and low cost approach to deposit uniform silicon dioxide layers on GaN by liquid phase deposition (LPD) near room temperature are described and discussed. The process is simple. GaN wafers are immersed into a H2SiF6 and H3BO3 solution to form the silicon dioxide layers. The deposition conditions and the properties of the SiO2 films will be characterized. (C) 2002 Elsevier Science B.V. All rights reserved.