Browsing by Author "Cheng, Hung-Hsiang"

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Electrooptical Properties of InGaAs/GaAs Strained Single Quantum Wells
(2000)
Lu, Chien-Rong
;
Lou, Shry-Fong
;
Cheng, Hung-Hsiang
;
Lee, Chien-Ping
;
Tsai, Fu-Yi
The electrooptical properties of (100) and (111)B InGaAs/GaAs strained single quantum wells have been studied by the photoreflectance spectroscopy at various temperatures and under different biases. There is a Si delta-doping sheet under the GaAs surface to screen the surface built-in electric field from the quantum well. The spectral features consist of the excitonic interband transitions in the quantum well, and the Franz-Keldysh oscillations from the band edge transitions of the GaAs barrier near the surface. The piezoelectric field tilts the (111)B single quantum well toward the Si delta-doping and causes subband filling by the electrons from the delta-doping centers. With a proper external bias to repel electrons from the tilted quantum well, the excitonic interband transition in the (111)B system is enhanced.
Localized electrochemical oxidation of p-GaAs(100) using atomic force microscopy with a carbon nanotube probe
(2006-08-14)
Huang, Wu-Ping
;
Cheng, Hung-Hsiang
;
Jian, Sheng-Rui
;
Chuu, Der-San
;
Hsieh, Jin-Yuan
The nanometre-scale oxidation characteristics of a p-GaAs(100) surface are investigated by atomic force microscope (AFM) electrochemical nanolithography with a multiwalled carbon nanotube (MWCNT) probe. The electrochemical parameters, such as anodizing voltages, scanning rate and modulated voltages, and how they affect the creation and growth of the oxide nanostructures are explored. The present results reveal that the initial growth rate (similar to 600 nm s(-1) for 10 V) decreases rapidly as the electric field strength is decreased. The oxide practically ceases to grow as the electric field is reduced to the order of similar to 1.2 x 10(7) V cm(-1). Also, the oxide growth rate depends not only on the electric field strength but also on the applied anodizing voltage. The present results show that the height of the oxide structures can be significantly improved at an applied anodizing voltage of 10 V by using a CNT probe. In addition, Auger electron spectroscopy (AES) measurements performed in the present work confirm that modified structures replace the form of anodizing p-GaAs(100).
Temperature-dependent electroluminescence from GeSn heterojunction light-emitting diode on Si substrate
(2016-04-01)
Chang, Chiao
;
Li, Hui
;
Huang, Ssu-Hsuan
;
Lin, Li-Chien
;
Cheng, Hung-Hsiang
The electroluminescence from a Ge/GeSn/Ge p-i-n light-emitting diode on Si was investigated under different temperatures ranging from 25 to 150 K. The diode was operated at a low injection current density of 13A/cm(2). We obtained no-phonon-and phonon-assisted replicas in emission spectra. Also, the relationship between indirect bandgap energy and temperature was investigated. The temperature-dependent bandgap energy followed Varshni's empirical expression with alpha = 4.884 x 10(-4) eV/K and beta = 130 K. (C) 2016 The Japan Society of Applied Physics
Temperature-dependent electroluminescence from GeSn heterojunction light-emitting diode on Si substrate
(2016-04)
Chang, Chiao
;
Li, Hui
;
Huang, Ssu-Hsuan
;
Lin, Li-Chien
;
Cheng, Hung-Hsiang
The electroluminescence from a Ge/GeSn/Ge p-i-n light-emitting diode on Si was investigated under different temperatures ranging from 25 to 150 K. The diode was operated at a low injection current density of 13A/cm(2). We obtained no-phonon-and phonon-assisted replicas in emission spectra. Also, the relationship between indirect bandgap energy and temperature was investigated. The temperature-dependent bandgap energy followed Varshni\'s empirical expression with alpha = 4.884 x 10(-4) eV/K and beta = 130 K. (C) 2016 The Japan Society of Applied Physics