Browsing by Author "FAN, JC"

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ALGAAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS ON SI SUBSTRATE USING EPITAXIAL LIFT-OFF
(1995-09-01)
FAN, JC
;
LEE, CP
;
HWANG, JA
;
HWANG, JH
;
電子工程學系及電子研究所
Epitaxial lift-off (ELO) technique was used for the first time to transplant AlGaAs/GaAs Heterojunction Bipolar Transistors (HBT's) to Si substrates. Both preprocessed (devices processed before transplantation) and postprocessed (devices processed after transplantation) ELO HBT's On Si were demonstrated in this study. The characteristics of those HBT's on Si with either technique show nearly identical characteristics of the HBT's on GaAs without transplantation, indicating the film quality is maintained after transplantation. Devices with a high current gain of 550 were transplanted without any degradation, and the current gain is not limited by the ELO process. This current gain value is the highest reported for GaAs HBT's on Si with any techniques.
ALGAAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS ON SI SUBSTRATE USING EPITAXIAL LIFT-OFF
(1995-09-01)
FAN, JC
;
LEE, CP
;
HWANG, JA
;
HWANG, JH
;
電子工程學系及電子研究所
Epitaxial lift-off (ELO) technique was used for the first time to transplant AlGaAs/GaAs Heterojunction Bipolar Transistors (HBT's) to Si substrates. Both preprocessed (devices processed before transplantation) and postprocessed (devices processed after transplantation) ELO HBT's On Si were demonstrated in this study. The characteristics of those HBT's on Si with either technique show nearly identical characteristics of the HBT's on GaAs without transplantation, indicating the film quality is maintained after transplantation. Devices with a high current gain of 550 were transplanted without any degradation, and the current gain is not limited by the ELO process. This current gain value is the highest reported for GaAs HBT's on Si with any techniques.
COMPOSITIONAL DISORDERING OF ALGAAS/GAAS SUPERLATTICES BY USING THE LOW-TEMPERATURE-GROWN GAAS
(1995-07-01)
TSANG, JS
;
LEE, CP
;
FAN, JC
;
TSAI, KL
;
CHEN, HR
The use of low-temperature (similar to 200 degrees C) grown GaAs by molecular beam epitaxy to induce compositional disordering of AlGaAs/GaAs superlattices has been studied. After furnace annealing between 700 and 850 degrees C for 30 min, an obvious blue shift in the peak wavelength of the superlattice emission is observed by the 77 K photoluminescence (PL), indicating that the emission has been changed from that of the GaAs quantum wells to that of the intermixed AlGaAs. The PL shift and the depth profile of Al concentration measured by secondary ion mass spectrometry indicate that the superlattice is nearly totally disordered after 850 degrees C annealing. (C) 1995 American Vacuum Society.
DIRECT OBSERVATION OF SI DELTA-DOPED GAAS BY TRANSMISSION ELECTRON-MICROSCOPY
(1992-05-25)
LIU, DG
;
FAN, JC
;
LEE, CP
;
TSAI, CM
;
CHANG, KH
Direct observation of the Si delta-doped layer in GaAs has been achieved by high resolution transmission electron microscopy. Samples with different Si doses, from half a monolayer to two monolayers, were studied. The observed spreading of the delta-doped layer showed that Si atoms are largely confined in five monolayers at most (in the highest dose case), indicating excellent confinements of dopants in GaAs. From the images, the Si atoms were uniformly distributed in the doped layer, no cluster formation was observed. For delta-doped GaAs grown at low temperature (480-degrees-C), stacking faults originated from the doped layers were observed. These faults were thought to be caused by the large unrelaxed strain in the low-temperature grown GaAs.
EFFECTS OF LOW-TEMPERATURE-GROWN GAAS LAYER ON COMPOSITIONAL DISORDERING OF ALGAAS/GAAS SUPERLATTICES
(1995-02-01)
TSANG, JS
;
LEE, CP
;
FAN, JC
;
LEE, SH
;
TSAI, KL
Effects of thickness and position of the low-temperature-grown GaAs (LT-GaAs) layer on the compositional disordering of AlGaAs/GaAs superlattice have been studied. Samples with a top LT-GaAs layer or a bottom LT-GaAs layer have been studied with various annealing conditions. It was found that the LT-GaAs layer grown on top of the superlattice is more effective in causing disordering than the LT-GaAs layer grown at the bottom. The amount of disordering increases with the thickness of the LT-GaAs layer. A selective disordering process has been developed using a patterned LT-GaAs cap layer. This disordering technique is very simple and can be easily applied to device fabrication.
INFLUENCE OF THIN PROTECTIVE INAS LAYERS ON THE OPTICAL-QUALITY OF ALGAAS AND QUANTUM-WELLS
(1992-09-15)
TSAI, KL
;
CHANG, KH
;
LEE, CP
;
HUANG, KF
;
CHANG, Y
Influence of a thin protective but subsequently evaporated InAs layer on the regrowth of AlGaAs has been studied. It was found tha although most of the InAs could be evaporated by thermal desorption, some would react with Al0.36Ga0.64As to form InAlGaAs. These InAlGaAs islands act as potential wells for carrier recombination and dominate the photoluminescence spectrum. Transmission electron microscopy photographs show that dislocations are formed near the islands. These defects are caused by lattice mismatch between AlGaAs and InAlGaAs. These islands and defects strongly affect the optical quality of surrounding Al0.36Ga0.64As and quantum wells.
TRANSMISSION ELECTRON-MICROSCOPY STUDY OF HEAVILY DELTA-DOPED GAAS GROWN BY MOLECULAR-BEAM EPITAXY
(1993-01-15)
LIU, DG
;
FAN, JC
;
LEE, CP
;
CHANG, KH
;
LIOU, DC
N-type and p-type delta-doped GaAs grown by molecular beam epitaxy with rather significantly high doses of Si and Be have been investigated by transmission electron microscopy (TEM). The amount of doses ranged from half a monolayer to two monolayers. The microscopic structures of the delta-doped regions and the adjacent epilayers were directly observed by TEM. The effect of impurity spreading on the heterointerfaces and superlattices was also studied. Si atoms present in Si delta-doped samples were confined to within a few atomic layers. The Be atoms present in Be delta-doped samples, however, spread over a quite wide region and caused rough heterointerfaces and wavy superlattices to form. Spreading of Be was attributed to segregation and diffusion which occurred during growth. Stacking faults were found in the delta-doped samples when they were grown at low temperatures. They could be attributed to local strain caused by heavy doping.