Browsing by Author "Sheu, JK"

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Characterization of p-type InxGa1-xN grown by metalorganic chemical vapor deposition
(2001-03-01)
Wen, TC
;
Lee, WI
;
Sheu, JK
;
Chi, GC
;
友訊交大聯合研發中心
This study investigates the electrical and optical characteristics of Mg-doped InxGa1-xN grown by metalorganic chemical vapor deposition. All the Mg-doped InxGa1-xN layers show p-type conduction after thermal annealing. Room temperature (RT) carrier concentration increases exponentially with an In mole fraction increase. The highest hole concentration of bull; Mg-doped InxGa1-xN is 1.65 x 10(19) cm(-3). Also, the RT photoluminescence (PL) spectra of Mg related emissions in InxGa1-xN are displayed. However, the PL peak intensity becomes weak after the post-annealing process on Mg-doped InxGa1-xN. This degradation might be created by the surface dissociation during the post-annealing process. (C) 2001 Elsevier Science Ltd. All rights reserved.
Fabrication and characterization of In(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods
(2005-10-01)
Hsueh, TH
;
Sheu, JK
;
Huang, HW
;
Chang, YH
;
Ou-Yang, MC
ln(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods with diameters of 60-100nm were fabricated by inductively coupled plasma reactive ion etching with Cl(2)/Ar plasma. The strong optical emission of the nanorods, observed by micro-photoluminescence measurement at 80 K, reveals a large blue shift of about 90meV and an increase in photoluminescence intensity density of more than 17-fold, compared with that of the as-grown wafer under the same excitation power density of 80W/cm(2). These nanostructures have a high potential for application in efficient GaN-based vertical cavity emitters.
Fabrication and characterization of In0.25Ga0.75N/GaN multiple quantum wells embedded in nanorods
(2005-10-01)
Hsueh, TH
;
Sheu, JK
;
Huang, HW
;
Chang, YH
;
Ou-Yang, MC
ln(0.25)Ga(0.75)N/GaN multiple quantum wells embedded in nanorods with diameters of 60-100nm were fabricated by inductively coupled plasma reactive ion etching with Cl-2/Ar plasma. The strong optical emission of the nanorods, observed by micro-photoluminescence measurement at 80 K, reveals a large blue shift of about 90meV and an increase in photoluminescence intensity density of more than 17-fold, compared with that of the as-grown wafer under the same excitation power density of 80W/cm(2). These nanostructures have a high potential for application in efficient GaN-based vertical cavity emitters.
Observation of dislocation etch pits in epitaxial lateral overgrowth GaN by wet etching
(2002-04-01)
Wen, TC
;
Lee, WI
;
Sheu, JK
;
Chi, GC
;
電子物理學系
This work investigates dislocation etch pits in epitaxial lateral overgrowth (ELO) GaN by wet etching. A mixture of H2SO4 and H3PO4 was used as an etching solution. SEM and AFM were employed to observe the surface topography. For the as-grown sample, SEM images show the flat, smooth surface without any pits or hillocks. After the chemical etching, hexagonal shaped etch pits were observed at the edge of ELO GaN. AFM observation of etched ELO GaN displayed high densities of etch pits clustered in the "window" region and the coalescent line of two growing fronts. In contrast, the overgrowth region was nearly free of etch pits. Moreover, we observed that different sizes of etch pits dominated in "window" region and coalescent region. This implied different types dislocations dominated in these regions. (C) 2002 Elsevier Science Ltd. All rights reserved.
Photoluminescence from In0.3Ga0.7N/GaN multiple-quantum-well nanorods
(2005-04-01)
Hsueh, TH
;
Huang, HW
;
Lai, FI
;
Sheu, JK
;
Chang, YH
The fabrication of ln(0.3)Ga(0.7)N/GaN multiple-quantum-well nanorods with diameters of 60-100 nm and their optical characteristics performed by micro-photoluminescence measurements are presented. The nanorods were fabricated by inductively coupled plasma dry etching from a light-emitting diode wafer. The structure and surface properties of fabricated nanorods were verified by the field emission scanning electron microscopy and the transmission electron microscopy. The photoluminescence (PL) spectra with sharp linewidths of typically 1.5 nm were observed at 4 K. The excitation-power-dependent spectra show that no energy shift was observed for these sharp peaks. Moreover, increasing the excitation power instead leads to an occurrence of new, sharp PL peaks at the higher energy tail of the PL spectra, which suggest that excitons are strongly confined in quantum-dot-like regions or localization centres.