Browsing by Author "Lee, Shih-Chang"

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Extended microtunnels in GaN prepared by wet chemical etch
(2006-11-13)
Huang, Hsin-Hsiung
;
Zeng, Hung-Yu
;
Lee, Chi-Ling
;
Lee, Shih-Chang
;
Lee, Wei-I
It is demonstrated in GaN that microtunnels extended beyond hundreds of microns can be easily achieved using wet chemical etch. To obtain this result, specially designed structures of GaN layers are first grown on sapphire substrates with metal-organic chemical vapor deposition and subsequently with hydride vapor phase epitaxy techniques. The prepared samples are then chemically etched in molten KOH. With the designed structure of GaN layers, extended microtunnels with triangular cross sections are formed. The crystallographic planes of the triangular bevels belong to the {11(2) over bar 2} family. The etch rate of the tunnel can be as high as 10 mu m/min at proper etching conditions. (c) 2006 American Institute of Physics.
Study the Al-oxide/GaAs Interface Characteristics by Spectral Response of GaAs Solar Cells
(2000)
Lee, Shih-Chang
;
Wen, Tzu-Chi
;
Lee, Wei-I
;
電子物理學系
;
Department of Electrophysics
The Al-oxide formed by wet-thermal oxidation of AlAs is used as the anti-reflection (AR) coating of the GaAs solar cell. Results of spectral response measurement suggest that the interfacial recombination velocity is extremely high at the Al-oxide/GaAs interface. Adding a 20-nm-thick Al0.4Ga0.6As barrier layer between the Al-oxide and the GaAs emitter can reduce the influence of interfacial recombination and enhance the performance of the GaAs solar cell. The energy conversion efficiency of the GaAs solar cell utilizing the wet oxidation of AlAs to form the AR coating is 19.43% under the luminescence condition of one-sun, AM 1.5G and 100 mW/cm(2).